Category: Coding

June 14, 2015

Writing my first iPhone app – Day 6 – Its all coming together

Finally managed to unpack everything after moving flats so no more boxes, yey! Unfortunately somehow managed to lose the box with my socks and underwear tho. Oh well, you win some you lose some. Anyway, had some time today to work on this app of mine.

First of all I wanted to pretty it up a little bit. I have no sense of style at all (don’t think any coder does) but I do not like working with anything too messy. So here are a couple of things I did to make me feel more comfortable:

I’ve reordered my tabs in my TabBarController to make the “Play” item to be in the center. For much of my surprise the storyboard editor doesn’t let me select the default tab. I realized that I have to extend the TabBarController. So after much research I found a code snippet that did the trick

class TabBarController: UITabBarController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.selectedIndex = 1 
        
        let barbuttonFont = UIFont(name: "Ubuntu-Light", size: 11) ?? UIFont.systemFontOfSize(11)
        
        UITabBar.appearance().tintColor = UIColor.whiteColor()
        UITabBarItem.appearance().setTitleTextAttributes([NSFontAttributeName: barbuttonFont, NSForegroundColorAttributeName:UIColor.whiteColor()], forState: UIControlState.Normal)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    
}

class TabBarController: UITabBarController {

override func viewDidLoad() {

super.viewDidLoad()

self.selectedIndex = 1

let barbuttonFont = UIFont(name: "Ubuntu-Light", size: 11) ?? UIFont.systemFontOfSize(11)

UITabBar.appearance().tintColor = UIColor.whiteColor()

UITabBarItem.appearance().setTitleTextAttributes([NSFontAttributeName: barbuttonFont, NSForegroundColorAttributeName:UIColor.whiteColor()], forState: UIControlState.Normal)

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

I’ve also made the tab bar’s color scheme inverse so the above code takes care of the font colors as well. I also wanted to display a heading on all pages with a title so dragged in a Navigation Controller and connected it to my Tab Bar Controller. It displayed the heading placeholder but I couldn’t find a way in the storyboard editor to set the text for each tab element. Clever people of stack overflow said that i can set the title from the ViewDidAppear method of each controller. Here is an example of how:

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        
        self.tabBarController?.title = "Play BillionQuestions"
    }

override func viewDidAppear(animated: Bool) {

super.viewDidAppear(animated)

self.tabBarController?.title = "Play BillionQuestions"

}

Since I really don’t like the UIColor API (coming from web development background I think it’s understandable) I was looking for an easy to use alternative. Thats how i found UIColorExtension. Its a simple extension that allows me to use RGB(a) hex codes in my color definitions. So I can write stuff like this:

    UITabBar.appearance().tintColor = UIColor(rgba: "#ffffff")

1	UITabBar.appearance().tintColor = UIColor(rgba: "#ffffff")

Winning (except for the 15 minutes it took me how to do # on a mac keyboard)

Also replaced my label that was used for the countdown with a Progress View. Progress View’s are really straight forward to use:

    func subtractTime(){
        self.seconds--
        countDownTimerLabel.text = "\(self.seconds)s"
        
        let fractionalProgress = Float(self.seconds) / 30.0
        let animated = self.seconds != 0
        self.progressBar.setProgress(fractionalProgress, animated: animated)
        
        
        if (self.seconds == 0) {
            self.timer.invalidate()
            self.disableButtons()
            self.highlightCorrectAnswer()
            
            countDownTimerLabel.text = "Out of Time"
            nextQuestionButton.hidden = false
            self.logResult(-1, correct: 0)
        }
    }
    
    func startCountDown(){
        self.seconds = 30
        countDownTimerLabel.text = "\(self.seconds)s"
        countDownTimerLabel.textColor = UIColor.darkGrayColor()
        countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 20)
        
        self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("subtractTime"), userInfo: nil, repeats: true)
        
    }

func subtractTime(){

self.seconds--

countDownTimerLabel.text = "\(self.seconds)s"

let fractionalProgress = Float(self.seconds) / 30.0

let animated = self.seconds != 0

self.progressBar.setProgress(fractionalProgress, animated: animated)

if (self.seconds == 0) {

self.timer.invalidate()

self.disableButtons()

self.highlightCorrectAnswer()

countDownTimerLabel.text = "Out of Time"

nextQuestionButton.hidden = false

self.logResult(-1, correct: 0)

}

func startCountDown(){

self.seconds = 30

countDownTimerLabel.text = "\(self.seconds)s"

countDownTimerLabel.textColor = UIColor.darkGrayColor()

countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 20)

self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("subtractTime"), userInfo: nil, repeats: true)

}

All right. I think I’m done with prettying stuff up. It is still ugly as fuck but bit easier on the eye:

I hooked it up with the question API I made in my previous post and it worked like a charm. Except one thing: Since the API was using random sometimes it gave me the same question twice. In order to avoid that I needed to log the user’s answers. So created a new table:

CREATE TABLE `user_answers` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `user_id` int(11) NOT NULL,
 `question_id` int(11) NOT NULL,
 `answer` tinyint(4) NOT NULL,
 `correct` tinyint(4) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `user_id` (`user_id`),
 KEY `question_id` (`question_id`),
 KEY `answer` (`answer`),
 KEY `correct` (`correct`)
) DEFAULT CHARSET=utf8

CREATE TABLE `user_answers` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`user_id` int(11) NOT NULL,

`question_id` int(11) NOT NULL,

`answer` tinyint(4) NOT NULL,

`correct` tinyint(4) NOT NULL,

PRIMARY KEY (`id`),

KEY `user_id` (`user_id`),

KEY `question_id` (`question_id`),

KEY `answer` (`answer`),

KEY `correct` (`correct`)

) DEFAULT CHARSET=utf8

And a new class:

class Answer extends Model {

    public $db = null;
    public $schema = array( "id"    =>  array("type" => "int",
                                              "unique" => true,
                                              "notnull" => true,
                                              "nice_name" => "Id"),

                            "question_id" =>  array( "type" => "int",
                                                  "unique" => false,
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "QuestionId"),
                            "user_id" =>  array( "type" => "int",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "UserId"),
                            "answer" =>  array( "type" => "int",
                                                  "required" => true,
                                                  "nice_name" => "Answer"),
                            "correct" =>  array( "type" => "int",
                                                  "required" => true,
                                                  "nice_name" => "Correct")
                            );
    public $table = "user_answers";
    public $nice_name = "Answer";

    function __construct($db){
        global $baseurl, $basepath;

        $this->db = $db;
    }

}

class Answer extends Model {

public $db = null;

public $schema = array( "id" => array("type" => "int",

"unique" => true,

"notnull" => true,

"nice_name" => "Id"),

"question_id" => array( "type" => "int",

"unique" => false,

"required" => true,

"notnull" => true,

"nice_name" => "QuestionId"),

"user_id" => array( "type" => "int",

"required" => true,

"notnull" => true,

"nice_name" => "UserId"),

"answer" => array( "type" => "int",

"required" => true,

"nice_name" => "Answer"),

"correct" => array( "type" => "int",

"required" => true,

"nice_name" => "Correct")

);

public $table = "user_answers";

public $nice_name = "Answer";

function __construct($db){

global $baseurl, $basepath;

$this->db = $db;

}

The PHP API has been modified a little as well to able to record answers + avoid sending the same question to the same user again:

	public function getUserQuestions($user_id){
		$questions = array();
		$res = $this->answer_api->get(array("user_id" => $user_id), 0);
		foreach($res as $row_id => $row){
			$questions[] = $row['question_id'];
		}

		return $questions;
	}

	public function answer(){
		$errors = $this->answer_api->validate($this->params);
		if (!empty($errors)){
			$this->raiseError(json_encode($errors));
		}

		$this->answer_api->add($this->params);

	}

	public function question(){

		if (!isset($this->params['user_id']) || !$this->params['user_id']){
			$this->raiseError("missing param: user_id");
		}

		$question_ids = $this->getUserQuestions($this->params['user_id']);
		if (empty($question_ids)){
			$query = "SELECT * FROM questions ORDER BY rand() LIMIT 1";
		} else {
			$query = "SELECT * FROM questions WHERE id NOT IN (".implode(",", $question_ids).") ORDER BY rand() LIMIT 1";
		}

		$res = $this->db->query($query) or die($this->db->error." on line #".__LINE__);
		if ($res->num_rows){
			$row = $res->fetch_assoc();

			$ret = array();
			$ret['id'] = (int) $row['id'];
			$ret['question'] = $row['question'];
			$ret['category'] = $row['category'];
			$ret['correct'] = (int) $row['correct_answer'];
			$ret['current_post'] = 100000000; // TODO
			$ret['answers'] = array(
				$row['answer1'],
				$row['answer2'],
				$row['answer3'],
				$row['answer4']
			);

			print(json_encode($ret));
		}
	}

public function getUserQuestions($user_id){

$questions = array();

$res = $this->answer_api->get(array("user_id" => $user_id), 0);

foreach($res as $row_id => $row){

$questions[] = $row['question_id'];

}

return $questions;

}

public function answer(){

$errors = $this->answer_api->validate($this->params);

if (!empty($errors)){

$this->raiseError(json_encode($errors));

}

$this->answer_api->add($this->params);

}

public function question(){

if (!isset($this->params['user_id']) || !$this->params['user_id']){

$this->raiseError("missing param: user_id");

}

$question_ids = $this->getUserQuestions($this->params['user_id']);

if (empty($question_ids)){

$query = "SELECT * FROM questions ORDER BY rand() LIMIT 1";

} else {

$query = "SELECT * FROM questions WHERE id NOT IN (".implode(",", $question_ids).") ORDER BY rand() LIMIT 1";

}

$res = $this->db->query($query) or die($this->db->error." on line #".__LINE__);

if ($res->num_rows){

$row = $res->fetch_assoc();

$ret = array();

$ret['id'] = (int) $row['id'];

$ret['question'] = $row['question'];

$ret['category'] = $row['category'];

$ret['correct'] = (int) $row['correct_answer'];

$ret['current_post'] = 100000000; // TODO

$ret['answers'] = array(

$row['answer1'],

$row['answer2'],

$row['answer3'],

$row['answer4']

);

print(json_encode($ret));

}

Great, now the only thing left to do is to make the app send home the user’s answer for logging. In my PlayViewController I modified the logic that happens when the user clicks one of the answer buttons:

    func logResult(answer: Int, correct: Int){
        var url : String = "http://billion.lepunk.co.uk/api/"
        var request : NSMutableURLRequest = NSMutableURLRequest()
        var bodyData = "method=answer&user_id=\(self.userId)&question_id=\(self.currentQuestionId)&answer=\(answer)&correct=\(correct)"
        println(bodyData)
        request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);
        request.URL = NSURL(string: url)
        request.HTTPMethod = "POST"
        
        NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
        })
    }
    
    func highlightCorrectAnswer(){
        switch(self.currentCorrectAnswer){
            case 0: self.answer1Button.backgroundColor = UIColor(rgba: "#00aa00")
            case 1: self.answer2Button.backgroundColor = UIColor(rgba: "#00aa00")
            case 2: self.answer3Button.backgroundColor = UIColor(rgba: "#00aa00")
            case 3: self.answer4Button.backgroundColor = UIColor(rgba: "#00aa00")
            default:  self.answer1Button.backgroundColor = UIColor(rgba: "#00aa00")
        }
    }
    
    @IBAction func sendAnswer(sender: UIButton) {
        let buttonIndex = sender.tag
        var correct = 0
        
        self.timer.invalidate()
        self.disableButtons()
        
        if (buttonIndex == self.currentCorrectAnswer){
            correct = 1
            sender.backgroundColor = UIColor(rgba: "#00aa00")
        } else {
            sender.backgroundColor = UIColor(rgba: "#aa0000")
            self.highlightCorrectAnswer()
        }
        
        nextQuestionButton.hidden = false
        
        logResult(buttonIndex, correct: correct)
        
    }

func logResult(answer: Int, correct: Int){

var url : String = "http://billion.lepunk.co.uk/api/"

var request : NSMutableURLRequest = NSMutableURLRequest()

var bodyData = "method=answer&user_id=\(self.userId)&question_id=\(self.currentQuestionId)&answer=\(answer)&correct=\(correct)"

println(bodyData)

request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);

request.URL = NSURL(string: url)

request.HTTPMethod = "POST"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in

})

}

func highlightCorrectAnswer(){

switch(self.currentCorrectAnswer){

case 0: self.answer1Button.backgroundColor = UIColor(rgba: "#00aa00")

case 1: self.answer2Button.backgroundColor = UIColor(rgba: "#00aa00")

case 2: self.answer3Button.backgroundColor = UIColor(rgba: "#00aa00")

case 3: self.answer4Button.backgroundColor = UIColor(rgba: "#00aa00")

default: self.answer1Button.backgroundColor = UIColor(rgba: "#00aa00")

}

@IBAction func sendAnswer(sender: UIButton) {

let buttonIndex = sender.tag

var correct = 0

self.timer.invalidate()

self.disableButtons()

if (buttonIndex == self.currentCorrectAnswer){

correct = 1

sender.backgroundColor = UIColor(rgba: "#00aa00")

} else {

sender.backgroundColor = UIColor(rgba: "#aa0000")

self.highlightCorrectAnswer()

}

nextQuestionButton.hidden = false

logResult(buttonIndex, correct: correct)

}

When the user hits the button it just checks against self.currentCorrectAnswer and depending on the result it sends home the questionId, userId and 0 or 1 for logging.

Finally I decided to make this project fully open source. Please feel free to fork / do a pull request / whatever, but keep in mind it is very much a work in progress and I have literally no idea what am I doing in Swift

Repo for the app | Repo for the PHP Api and scraper(s)

The game is actually playable now and it is moderately entertaining. Will need to find a new source of questions because the current ones are way too British.

What is next? The gameplay is pretty much ready now. It needs some refactoring and some security on the API but its ok for now. Next time I’m going to work on the leaderboard view. Deal with some TableViews in xcode and probably implement Facebook friend list somehow.

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June 10, 2015

Writing my first iPhone app – Day 5

Ok, I’m cheating a little bit here. I did not work on the app during the past two weeks or so but I have very good reasons. First of all I moved to a new flat (which I absolutely love btw) and as you know moving is hard. Secondly the Macbook I borrowed from work pretty much died under me. It kept presenting the so called “black screen of death” 9 out of 10 times I tried to boot. Tried to do all the PRAM resets and mental keyboard combos I could find online but no joy. Anyway, bought the new generation Macbook Pro now (force touch trackpad rulez btw) so I’m back in business.

That being said yesterday I only worked on the back-end of the app. In order to go forward with the actual iOS development I needed some questions and answers in my database so I decided to look around to find a site which I can scrape. I’m really surprised that there are no good quiz sites around with 4 answers for each question and the correct answer included. Found some databases for sale that would fit my needs but the sales page were either crappy or the database was ridiculously overpriced. The only site I could find that met all my requirements is PubQuizArea, which ticks all the boxes, however it is really British. Oh well, it should do for now.

First of all I need a table structure:

CREATE TABLE `questions` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `question` varchar(500) COLLATE utf8_bin NOT NULL,
 `answer1` varchar(200) COLLATE utf8_bin NOT NULL,
 `answer2` varchar(200) COLLATE utf8_bin NOT NULL,
 `answer3` varchar(200) COLLATE utf8_bin NOT NULL,
 `answer4` varchar(200) COLLATE utf8_bin NOT NULL,
 `correct_answer` tinyint(4) NOT NULL,
 `category` varchar(200) COLLATE utf8_bin DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin

CREATE TABLE `questions` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`question` varchar(500) COLLATE utf8_bin NOT NULL,

`answer1` varchar(200) COLLATE utf8_bin NOT NULL,

`answer2` varchar(200) COLLATE utf8_bin NOT NULL,

`answer3` varchar(200) COLLATE utf8_bin NOT NULL,

`answer4` varchar(200) COLLATE utf8_bin NOT NULL,

`correct_answer` tinyint(4) NOT NULL,

`category` varchar(200) COLLATE utf8_bin DEFAULT NULL,

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin

The model for this is written with my No-BS Framework. It does not need to modify the base model at all, just need to define the table fields and some validation rules (question needs to be unique:

<?php

class Question extends Model {

    public $db = null;
    public $schema = array( "id"    =>  array("type" => "int",
                                              "unique" => true,
                                              "notnull" => true,
                                              "nice_name" => "Id"),

                            "question" =>  array( "type" => "string",
                                                  "unique" => true,
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Question"),
                            "answer1" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Answer1"),
                            "answer2" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Answer2"),
                            "answer3" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Answer3"),
                            "answer4" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Answer4"),
                            "correct_answer" =>  array(  "type" => "int",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Correct answer"),
                            "category" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => false,
                                                  "nice_name" => "Category"),
                            );
    public $table = "questions";
    public $nice_name = "Question";

    function __construct($db){
        global $baseurl, $basepath;

        $this->db = $db;
    }

}

<?php

class Question extends Model {

public $db = null;

public $schema = array( "id" => array("type" => "int",

"unique" => true,

"notnull" => true,

"nice_name" => "Id"),

"question" => array( "type" => "string",

"unique" => true,

"required" => true,

"notnull" => true,

"nice_name" => "Question"),

"answer1" => array( "type" => "string",

"required" => true,

"notnull" => true,

"nice_name" => "Answer1"),

"answer2" => array( "type" => "string",

"required" => true,

"notnull" => true,

"nice_name" => "Answer2"),

"answer3" => array( "type" => "string",

"required" => true,

"notnull" => true,

"nice_name" => "Answer3"),

"answer4" => array( "type" => "string",

"required" => true,

"notnull" => true,

"nice_name" => "Answer4"),

"correct_answer" => array( "type" => "int",

"required" => true,

"notnull" => true,

"nice_name" => "Correct answer"),

"category" => array( "type" => "string",

"required" => true,

"notnull" => false,

"nice_name" => "Category"),

);

public $table = "questions";

public $nice_name = "Question";

function __construct($db){

global $baseurl, $basepath;

$this->db = $db;

}

The main part of the job is writing a simple scraper. Luckily the site’s structure is pretty well thought out so it makes it easy to scrape:

<?php

// http://www.pubquizarea.com/multiple-choice/general-knowledge-quiz/start/&next=30/32/1/

set_time_limit(0);
ini_set("memory_limit", "1024M");

if (!isset($argv[1])){
    print("usage: php {$argv[0]} [URL]\n");
    exit();
}

require_once("../includes/curl.class.php");
require_once("../config.php");
require_once("../includes/model.class.php");
require_once("../includes/question.class.php");

$curl = new Curl();
$db = mysqlConnect($dbhost, $dbuser, $dbpass, $dbname);

$question = new Question($db);

$url = $argv[1];

while(true){
    print("getting main page: {$url}\n");

    $page = $curl->get($url);

    libxml_use_internal_errors(true);

    $dom = new DOMDocument();
    $dom->loadHTML($page);

    $links = $dom->getElementsByTagName('a');
    $next_url = null;

    $quizzes = array();
    for($i=0; $i<$links->length; $i++){
        $href = $links->item($i)->getAttribute("href");

        if (trim(strtolower($links->item($i)->textContent)) == "next" && substr_count($href, "&next=")){
            if ($href[0] == "/"){
                $next_url = "http://www.pubquizarea.com/".$href;
            } else {
                $next_url = "http://www.pubquizarea.com".$href;
            }
            
        }

        if (strpos($href, "view_question_and_answer_quizzes.php") !== 0){
            continue;
        }

        $quizzes[] = $href;
    }

    if (count($quizzes)){
        foreach($quizzes as $quiz_url){
            print($quiz_url."...\n");
            $page = $curl->get("http://www.pubquizarea.com/".$quiz_url);

            $dom = new DOMDocument();
            $dom->loadHTML($page);

            $h2s = $dom->getElementsByTagName('h2');
            if (!$h2s->length){
                continue;
            }

            $category = trim($h2s->item(0)->textContent);
            $category = preg_replace("/[^a-zA-Z0-9]+$/", "", $category);
            $category = preg_replace("/\s?\d+$/", "", $category);

            print("category: {$category}\n");

            $divs = $dom->getElementsByTagName('div');
            for($i=0; $i<$divs->length; $i++){
                $id = $divs->item($i)->getAttribute("id");

                if (strpos($id, "q_and_a_") !== 0){
                    continue;
                }

                $subdivs = $divs->item($i)->getElementsByTagName('div');

                $question_data = array();
                $question_data['answers'] = array();
                for($j=0; $j<$subdivs->length; $j++){
                    if ($subdivs->item($j)->getAttribute("class") == "left green"){
                        $question_data['question'] = preg_replace("/^\d+\.\ ?/", "", $subdivs->item($j)->textContent);
                    }

                    if ($subdivs->item($j)->getAttribute("class") == "written_quiz_answer"){
                        $question_data['answers'][] = trim($subdivs->item($j)->textContent);

                        $spans = $subdivs->item($j)->getElementsByTagName('span');
                        if ($spans->length){
                            for($k=0; $k<$spans->length; $k++){
                                if ($spans->item($k)->getAttribute("class") == "blue"){
                                    $question_data['correct_answer'] = count($question_data['answers']) - 1;
                                }
                            }
                        }
                    }
                }

                if (count($question_data['answers']) != 4 || !isset($question_data['correct_answer'])){
                    continue;
                }

                $db_data = array();
                $db_data['question'] = $question_data['question'];
                $db_data['answer1'] = $question_data['answers'][0];
                $db_data['answer2'] = $question_data['answers'][1];
                $db_data['answer3'] = $question_data['answers'][2];
                $db_data['answer4'] = $question_data['answers'][3];
                $db_data['correct_answer'] = $question_data['correct_answer'];
                $db_data['category'] = $category;
                
                $errors = $question->validate($db_data);
                if (!count($errors)){
                    $question->add($db_data);
                    print("added: {$db_data['question']}\n");
                }
            }
        }
    }

    // next page
    if (!$next_url){
        break;
    }

    $url = $next_url;

}

100

101

102

103

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<?php

// http://www.pubquizarea.com/multiple-choice/general-knowledge-quiz/start/&next=30/32/1/

set_time_limit(0);

ini_set("memory_limit", "1024M");

if (!isset($argv[1])){

print("usage: php {$argv[0]} [URL]\n");

exit();

}

require_once("../includes/curl.class.php");

require_once("../config.php");

require_once("../includes/model.class.php");

require_once("../includes/question.class.php");

$curl = new Curl();

$db = mysqlConnect($dbhost, $dbuser, $dbpass, $dbname);

$question = new Question($db);

$url = $argv[1];

while(true){

print("getting main page: {$url}\n");

$page = $curl->get($url);

libxml_use_internal_errors(true);

$dom = new DOMDocument();

$dom->loadHTML($page);

$links = $dom->getElementsByTagName('a');

$next_url = null;

$quizzes = array();

for($i=0; $i<$links->length; $i++){

$href = $links->item($i)->getAttribute("href");

if (trim(strtolower($links->item($i)->textContent)) == "next" && substr_count($href, "&next=")){

if ($href[0] == "/"){

$next_url = "http://www.pubquizarea.com/".$href;

} else {

$next_url = "http://www.pubquizarea.com".$href;

}

if (strpos($href, "view_question_and_answer_quizzes.php") !== 0){

continue;

}

$quizzes[] = $href;

}

if (count($quizzes)){

foreach($quizzes as $quiz_url){

print($quiz_url."...\n");

$page = $curl->get("http://www.pubquizarea.com/".$quiz_url);

$dom = new DOMDocument();

$dom->loadHTML($page);

$h2s = $dom->getElementsByTagName('h2');

if (!$h2s->length){

continue;

}

$category = trim($h2s->item(0)->textContent);

$category = preg_replace("/[^a-zA-Z0-9]+$/", "", $category);

$category = preg_replace("/\s?\d+$/", "", $category);

print("category: {$category}\n");

$divs = $dom->getElementsByTagName('div');

for($i=0; $i<$divs->length; $i++){

$id = $divs->item($i)->getAttribute("id");

if (strpos($id, "q_and_a_") !== 0){

continue;

}

$subdivs = $divs->item($i)->getElementsByTagName('div');

$question_data = array();

$question_data['answers'] = array();

for($j=0; $j<$subdivs->length; $j++){

if ($subdivs->item($j)->getAttribute("class") == "left green"){

$question_data['question'] = preg_replace("/^\d+\.\ ?/", "", $subdivs->item($j)->textContent);

}

if ($subdivs->item($j)->getAttribute("class") == "written_quiz_answer"){

$question_data['answers'][] = trim($subdivs->item($j)->textContent);

$spans = $subdivs->item($j)->getElementsByTagName('span');

if ($spans->length){

for($k=0; $k<$spans->length; $k++){

if ($spans->item($k)->getAttribute("class") == "blue"){

$question_data['correct_answer'] = count($question_data['answers']) - 1;

}

if (count($question_data['answers']) != 4 || !isset($question_data['correct_answer'])){

continue;

}

$db_data = array();

$db_data['question'] = $question_data['question'];

$db_data['answer1'] = $question_data['answers'][0];

$db_data['answer2'] = $question_data['answers'][1];

$db_data['answer3'] = $question_data['answers'][2];

$db_data['answer4'] = $question_data['answers'][3];

$db_data['correct_answer'] = $question_data['correct_answer'];

$db_data['category'] = $category;

$errors = $question->validate($db_data);

if (!count($errors)){

$question->add($db_data);

print("added: {$db_data['question']}\n");

}

// next page

if (!$next_url){

break;

}

$url = $next_url;

}

I know I know. Heard it million times: my scraping style is really old school. Guess what? I tried all those hipster libraries for scraping which promise you bells and whistles, none of those worked for me. Every once in a while they stop working and it is really hard to find the actual issue under the hood. As always I’m using my trusty curl class to fetch the data.

The script is just looping through the subpages of the category url from the command line argument and get the question / answer data from them. Luckily the correct answer is highlighted with a separate class (“blue”) so it is easy to recognize. $question->validate($db_data); takes care of removing dupes too.

That site gave me about ~1,800 questions. Obviously not enough, but will do for testing.

Last thing was to add an endpoint to my api. My __construct became:

	function __construct($db, $params){
		$this->db = $db;
		$this->user = new User($this->db);
		$this->question_api = new Question($this->db);
		$this->params = $params;

		if (!isset($params['method'])){
			$this->raiseError("No method provided");
		}

		if ($this->params['method'] == "register"){
			$this->register();
		} elseif ($this->params['method'] == "login"){
			$this->login();
		} elseif ($this->params['method'] == "question"){
			$this->question();
		} elseif ($this->params['method'] == "facebookLogin"){
			$this->facebookLogin();
		} elseif ($this->params['method'] == "stub"){
			$this->stub();
		} else {
			$this->raiseError("unknown method: {$this->params['method']}");
		}
	}

function __construct($db, $params){

$this->db = $db;

$this->user = new User($this->db);

$this->question_api = new Question($this->db);

$this->params = $params;

if (!isset($params['method'])){

$this->raiseError("No method provided");

}

if ($this->params['method'] == "register"){

$this->register();

} elseif ($this->params['method'] == "login"){

$this->login();

} elseif ($this->params['method'] == "question"){

$this->question();

} elseif ($this->params['method'] == "facebookLogin"){

$this->facebookLogin();

} elseif ($this->params['method'] == "stub"){

$this->stub();

} else {

$this->raiseError("unknown method: {$this->params['method']}");

}

And the implementation is:

	public function question(){
		$res = $this->db->query("SELECT * FROM questions ORDER BY rand() LIMIT 1") or die($this->db->error." on line #".__LINE__);
		if ($res->num_rows){
			$row = $res->fetch_assoc();

			$ret = array();
			$ret['id'] = $row['id'];
			$ret['question'] = $row['question'];
			$ret['category'] = $row['category'];
			$ret['correct'] = $row['correct_answer'];
			$ret['current_post'] = 100000000; // TODO
			$ret['answers'] = array(
				$row['answer1'],
				$row['answer2'],
				$row['answer3'],
				$row['answer4']
			);

			print(json_encode($ret));
		}
	}

public function question(){

$res = $this->db->query("SELECT * FROM questions ORDER BY rand() LIMIT 1") or die($this->db->error." on line #".__LINE__);

if ($res->num_rows){

$row = $res->fetch_assoc();

$ret = array();

$ret['id'] = $row['id'];

$ret['question'] = $row['question'];

$ret['category'] = $row['category'];

$ret['correct'] = $row['correct_answer'];

$ret['current_post'] = 100000000; // TODO

$ret['answers'] = array(

$row['answer1'],

$row['answer2'],

$row['answer3'],

$row['answer4']

);

print(json_encode($ret));

}

Obviously this logic will change as I hook it up with the app (rand() doesn’t exactly prevents the user from getting the same question over and over again) but again, its ok for testing. If you fancy trying it out, click here

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May 27, 2015

Crappy Fizz-Buzz

Read this article today on HN about 5 alternatives for fizzbuzz for coding interviews. The last one was to write the worst fizzbuzz program you can come up with. It sounded like something i should do before my morning coffee so here is my entry:

$limit = 100;

$prog = '$cntr = 1;'."\n";
$prog.= 'while($cntr <= '.$limit.'){'."\n";
$prog.= '	switch($cntr){'."\n";

for($i=1; $i<=$limit; $i++){
	if ($i % 3 == 0 &amp;&amp; $i % 5 == 0){
		$prog.= "		case $i:\n			print(\"fizzbuzz \"); break;\n";
	} elseif ($i % 3 == 0){
		$prog.= "		case $i:\n			print(\"fizz \"); break;\n";
	} elseif ($i % 5 == 0){
		$prog.= "		case $i:\n			print(\"buzz \"); break;\n";
	} else {
		$prog.= "		case $i:\n			print(\"$i \"); break;\n";
	}
}

$prog.= '	}'."\n";
$prog.= '	$cntr++;'."\n";
$prog.= '}'."\n";

eval($prog);

$limit = 100;

$prog = '$cntr = 1;'."\n";

$prog.= 'while($cntr <= '.$limit.'){'."\n";

$prog.= ' switch($cntr){'."\n";

for($i=1; $i<=$limit; $i++){

if ($i % 3 == 0 && $i % 5 == 0){

$prog.= " case $i:\n print(\"fizzbuzz \"); break;\n";

} elseif ($i % 3 == 0){

$prog.= " case $i:\n print(\"fizz \"); break;\n";

} elseif ($i % 5 == 0){

$prog.= " case $i:\n print(\"buzz \"); break;\n";

} else {

$prog.= " case $i:\n print(\"$i \"); break;\n";

}

$prog.= ' }'."\n";

$prog.= ' $cntr++;'."\n";

$prog.= '}'."\n";

eval($prog);

Can you do worse?

PS: No movement on my iPhone app today since I decided to get drunk yesterday

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May 26, 2015

Writing my first iPhone app – Day 4 – API integration

With the general framework of my front end’s register / login interface being done it’s time to create the API for handling user signup and login. I can’t stress it enough how great is it to work a little bit with the language I’m most familiar with after spending 3 days with Swift.

I will keep the database very simple for now:

CREATE TABLE `users` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `username` varchar(30) NOT NULL,
 `password` varchar(200) NOT NULL,
 `email` varchar(200) NOT NULL,
 `facebook_id` varchar(50) NOT NULL,
 PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8

CREATE TABLE `users` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`username` varchar(30) NOT NULL,

`password` varchar(200) NOT NULL,

`email` varchar(200) NOT NULL,

`facebook_id` varchar(50) NOT NULL,

PRIMARY KEY (`id`)

) DEFAULT CHARSET=utf8

For the API itself I’m going to use my No Bullshit Framework. The framework is very much in alpha stage but will speed up my development. I only need the model module from it so I’m gonna go ahead and copy the “includes” directory and the example config from the framework. I’m also going to create a user.class.php inside includes which will implement my interaction with my users table. Here is the pretty straight-forward code:

class User extends Model {

    public $db = null;
    public $schema = array( "id"    =>  array("type" => "int",
                                              "unique" => true,
                                              "notnull" => true,
                                              "nice_name" => "Id"),

                            "username" =>  array( "type" => "string",
                                                  "unique" => true,
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Username"),
                            "password" =>  array( "type" => "string",
                                                  "required" => true,
                                                  "notnull" => true,
                                                  "nice_name" => "Password"),
                            "email" =>  array(  "type" => "string",
                                                "unique" => true,
                                                "required" => true,
                                                "notnull" => true,
                                                "nice_name" => "Email address"),
                            "facebook_id" =>  array("type" => "string",
                                                    "unique" => true,
                                                    "nice_name" => "Facebook ID")
                            );
    public $table = "users";
    public $nice_name = "User";

    function __construct($db){
        global $baseurl, $basepath;

        $this->db = $db;
        $this->schema['thumbnail']['path'] = $basepath."/thumbs";
        $this->schema['thumbnail']['url_prefix'] = $baseurl."/thumbs";
    }

    public function validateEmail($email){
        $isValid = true;
        $atIndex = strrpos($email, "@");
        if (is_bool($atIndex) && !$atIndex){
            $isValid = false;
        }  else {
            $domain = substr($email, $atIndex+1);
            $local = substr($email, 0, $atIndex);
            $localLen = strlen($local);
            $domainLen = strlen($domain);
            if ($localLen < 1 || $localLen > 64){
                // local part length exceeded
                $isValid = false;
            } else if ($domainLen < 1 || $domainLen > 255){
                // domain part length exceeded
                $isValid = false;
            } else if ($local[0] == '.' || $local[$localLen-1] == '.'){
                // local part starts or ends with '.'
                $isValid = false;
            } else if (preg_match('/\\.\\./', $local)){
                // local part has two consecutive dots
                $isValid = false;
            } else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain)){
                // character not valid in domain part
                $isValid = false;
            } else if (preg_match('/\\.\\./', $domain)){
                // domain part has two consecutive dots
                $isValid = false;
            } else if (!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/',str_replace("\\\\","",$local))){
                // character not valid in local part unless 
                // local part is quoted
                if (!preg_match('/^"(\\\\"|[^"])+"$/',str_replace("\\\\","",$local))){
                    $isValid = false;
                }
            }
        }
        return $isValid;
    }

    public function validate($params, $update_id = false){
        $errors = parent::validate($params, $update_id);

        if (!isset($errors['email']) && !$this->validateEmail($params['email'])){
            $errors['email'] = "Invalid email address provided";
        }

        if (!isset($errors['username'])){
            if (strlen($params['username']) < 5 || strlen($params['username']) > 30){
                $errors['username'] = "Username must be between 5 and 30 characters";
            } elseif (preg_match("/[^a-zA-Z0-9_]/", $params['username'])){
                $errors['username'] = "Username can only contain alphanumeric characters";
            }
        }

        if (!isset($errors['password'])){
            if (strlen($params['password']) < 5){
                $errors['password'] = "Password must be at least 5 characters long";
            }
        }

        return $errors;
    }

    public function hashPassword($password){
        $iterations = 10;
        $salt = md5($password).";billion$";
        $hash = crypt($password, $salt);
        for ($i = 0; $i < 10; ++$i){             
            $hash = crypt($hash.$password, $salt);         
        }         
        return $hash;     
    }     

    public function add($params){         
        $params['password'] = $this->hashPassword($params['password']);
        return parent::add($params);
    }

}

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class User extends Model {

public $db = null;

public $schema = array( "id" => array("type" => "int",

"unique" => true,

"notnull" => true,

"nice_name" => "Id"),

"username" => array( "type" => "string",

"unique" => true,

"required" => true,

"notnull" => true,

"nice_name" => "Username"),

"password" => array( "type" => "string",

"required" => true,

"notnull" => true,

"nice_name" => "Password"),

"email" => array( "type" => "string",

"unique" => true,

"required" => true,

"notnull" => true,

"nice_name" => "Email address"),

"facebook_id" => array("type" => "string",

"unique" => true,

"nice_name" => "Facebook ID")

);

public $table = "users";

public $nice_name = "User";

function __construct($db){

global $baseurl, $basepath;

$this->db = $db;

$this->schema['thumbnail']['path'] = $basepath."/thumbs";

$this->schema['thumbnail']['url_prefix'] = $baseurl."/thumbs";

}

public function validateEmail($email){

$isValid = true;

$atIndex = strrpos($email, "@");

if (is_bool($atIndex) && !$atIndex){

$isValid = false;

} else {

$domain = substr($email, $atIndex+1);

$local = substr($email, 0, $atIndex);

$localLen = strlen($local);

$domainLen = strlen($domain);

if ($localLen < 1 || $localLen > 64){

// local part length exceeded

$isValid = false;

} else if ($domainLen < 1 || $domainLen > 255){

// domain part length exceeded

$isValid = false;

} else if ($local[0] == '.' || $local[$localLen-1] == '.'){

// local part starts or ends with '.'

$isValid = false;

} else if (preg_match('/\\.\\./', $local)){

// local part has two consecutive dots

$isValid = false;

} else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain)){

// character not valid in domain part

$isValid = false;

} else if (preg_match('/\\.\\./', $domain)){

// domain part has two consecutive dots

$isValid = false;

} else if (!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/',str_replace("\\\\","",$local))){

// character not valid in local part unless

// local part is quoted

if (!preg_match('/^"(\\\\"|[^"])+"$/',str_replace("\\\\","",$local))){

$isValid = false;

}

return $isValid;

}

public function validate($params, $update_id = false){

$errors = parent::validate($params, $update_id);

if (!isset($errors['email']) && !$this->validateEmail($params['email'])){

$errors['email'] = "Invalid email address provided";

}

if (!isset($errors['username'])){

if (strlen($params['username']) < 5 || strlen($params['username']) > 30){

$errors['username'] = "Username must be between 5 and 30 characters";

} elseif (preg_match("/[^a-zA-Z0-9_]/", $params['username'])){

$errors['username'] = "Username can only contain alphanumeric characters";

}

if (!isset($errors['password'])){

if (strlen($params['password']) < 5){

$errors['password'] = "Password must be at least 5 characters long";

}

return $errors;

}

public function hashPassword($password){

$iterations = 10;

$salt = md5($password).";billion$";

$hash = crypt($password, $salt);

for ($i = 0; $i < 10; ++$i){

$hash = crypt($hash.$password, $salt);

}

return $hash;

}

public function add($params){

$params['password'] = $this->hashPassword($params['password']);

return parent::add($params);

}

Simples, some email validation, some password hashing (not the best kind, I know), the rest is taken care of my the framework.

As for the API itself I’m going to create an “api” directory in the root folder of the project and add an index.php file:

require_once("../config.php");
require_once("../includes/model.class.php");
require_once("../includes/user.class.php");

header("Content-Type: application/json");

class API {

	public $db = null;
	public $user = null;
	public $params = null;

	function __construct($db, $params){
		$this->db = $db;
		$this->user = new User($this->db);
		$this->params = $params;

		if (!isset($params['method'])){
			$this->raiseError("No method provided");
		}

		if ($this->params['method'] == "register"){
			$this->register();
		} elseif ($this->params['method'] == "login"){
			$this->login();
		} elseif ($this->params['method'] == "facebookLogin"){
			$this->facebookLogin();
		} elseif ($this->params['method'] == "stub"){
			$this->stub();
		} else {
			$this->raiseError("unknown method: {$this->params['method']}");
		}
	}

	public function register(){
		$errors = $this->user->validate($this->params);
		if (empty($errors)){
			$user_id = json_encode($this->user->add($this->params));

			print(json_encode(array("errors" => array(), "user_id" => $user_id)));
		} else {
			print(json_encode(array("errors" => $errors)));
		}
	}

	public function stub(){
		$data = array( 
		        "question" =>  "Mi az: 2 fule van megsem szatyor?",
		        "answers" => array(
		                "Szatyor",
		                "Nyul bazdmeg",
		                "Apad",
		                "Makosbukta"
		        ),
		        "correct" => 1,
		        "current_pos" => 1000000000
		);

		print(json_encode($data));
	}

	public function facebookLogin(){
		$errors = array();
		if (!isset($this->params['facebook_id']) || !$this->params['facebook_id']){
			$errors['facebook_id'] = "Missing Facebook ID";
		} 

		if (empty($errors)){
			$res = $this->user->get(array("facebook_id" => $this->params['facebook_id']), 0, 1);
			if (empty($res)){
				print(json_encode(array("errors" => array("facebook_id" => "User does not exist"))));	
			} else {
				print(json_encode(array("errors" => array(), "user_id" => $res['id'])));	
			}
		} else {
			print(json_encode(array("errors" => $errors)));
		}		

	}

	public function login(){
		$errors = array();
		if (!isset($this->params['username']) || !$this->params['username']){
			$errors['username'] = "Please enter your username";
		}

		if (!isset($this->params['password']) || !$this->params['password']){
			$errors['password'] = "Please enter your password";
		}

		if (empty($errors)){
			$password_hash = $this->user->hashPassword($this->params['password']);
			if (substr_count($this->params['username'], "@")){
				$check = array("email" => $this->params['username'], "password" => $password_hash);
			} else {
				$check = array("username" => $this->params['username'], "password" => $password_hash);
			}

			$res = $this->user->get($check, 0, 1);
			if (empty($res)){
				print(json_encode(array("errors" => array("username" => "Invalid login details"))));	
			} else {
				print(json_encode(array("errors" => array(), "user_id" => $res['id'])));	
			}
		} else {
			print(json_encode(array("errors" => $errors)));
		}
	}

	public function raiseError($message){
		print(json_encode(array("errors" => $message)));
		exit();
	}

}

$params = array();

if (isset($_GET) && !empty($_GET)){
	$params = $_GET;
} elseif (isset($_POST) && !empty($_POST)){
	$params = $_POST;
}

$db = mysqlConnect($dbhost, $dbuser, $dbpass, $dbname);
$api = new API($db, $params);

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require_once("../config.php");

require_once("../includes/model.class.php");

require_once("../includes/user.class.php");

header("Content-Type: application/json");

class API {

public $db = null;

public $user = null;

public $params = null;

function __construct($db, $params){

$this->db = $db;

$this->user = new User($this->db);

$this->params = $params;

if (!isset($params['method'])){

$this->raiseError("No method provided");

}

if ($this->params['method'] == "register"){

$this->register();

} elseif ($this->params['method'] == "login"){

$this->login();

} elseif ($this->params['method'] == "facebookLogin"){

$this->facebookLogin();

} elseif ($this->params['method'] == "stub"){

$this->stub();

} else {

$this->raiseError("unknown method: {$this->params['method']}");

}

public function register(){

$errors = $this->user->validate($this->params);

if (empty($errors)){

$user_id = json_encode($this->user->add($this->params));

print(json_encode(array("errors" => array(), "user_id" => $user_id)));

} else {

print(json_encode(array("errors" => $errors)));

}

public function stub(){

$data = array(

"question" => "Mi az: 2 fule van megsem szatyor?",

"answers" => array(

"Szatyor",

"Nyul bazdmeg",

"Apad",

"Makosbukta"

"correct" => 1,

"current_pos" => 1000000000

);

print(json_encode($data));

}

public function facebookLogin(){

$errors = array();

if (!isset($this->params['facebook_id']) || !$this->params['facebook_id']){

$errors['facebook_id'] = "Missing Facebook ID";

}

if (empty($errors)){

$res = $this->user->get(array("facebook_id" => $this->params['facebook_id']), 0, 1);

if (empty($res)){

print(json_encode(array("errors" => array("facebook_id" => "User does not exist"))));

} else {

print(json_encode(array("errors" => array(), "user_id" => $res['id'])));

}

} else {

print(json_encode(array("errors" => $errors)));

}

public function login(){

$errors = array();

if (!isset($this->params['username']) || !$this->params['username']){

$errors['username'] = "Please enter your username";

}

if (!isset($this->params['password']) || !$this->params['password']){

$errors['password'] = "Please enter your password";

}

if (empty($errors)){

$password_hash = $this->user->hashPassword($this->params['password']);

if (substr_count($this->params['username'], "@")){

$check = array("email" => $this->params['username'], "password" => $password_hash);

} else {

$check = array("username" => $this->params['username'], "password" => $password_hash);

}

$res = $this->user->get($check, 0, 1);

if (empty($res)){

print(json_encode(array("errors" => array("username" => "Invalid login details"))));

} else {

print(json_encode(array("errors" => array(), "user_id" => $res['id'])));

}

} else {

print(json_encode(array("errors" => $errors)));

}

public function raiseError($message){

print(json_encode(array("errors" => $message)));

exit();

}

$params = array();

if (isset($_GET) && !empty($_GET)){

$params = $_GET;

} elseif (isset($_POST) && !empty($_POST)){

$params = $_POST;

}

$db = mysqlConnect($dbhost, $dbuser, $dbpass, $dbname);

$api = new API($db, $params);

This implements everything I need from this API right now. Added a new DNS entry billion.lepunk.co.uk and pointed it to my server where the code is deployed. This way I can test the app with actual networking.

Back to the app, back to Xcode, back to OSX. In my register view I’ve added a couple of new things:

A hidden input field to store the user’s Facebook ID once they connected
A hidden label for explaining some stuff to Facebook users

I should not touch the original validation code in my doRegister function but need to update what happens once the form is validated:

        if (!hasError){
            // lets talk to the server
            var url : String = "http://billion.lepunk.co.uk/api/"
            var request : NSMutableURLRequest = NSMutableURLRequest()
            var bodyData = "method=register&username=\(username)&email=\(email)&password=\(passwd)&facebook_id=\(facebookId)"
            request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);
            request.URL = NSURL(string: url)
            request.HTTPMethod = "POST"
            
            NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
                var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
                
                var statusCode = 0
                if let httpResponse = response as? NSHTTPURLResponse {
                    statusCode = httpResponse.statusCode
                }
                
                if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){
                    dispatch_async(dispatch_get_main_queue(), {
                        self.emailErrorLabel.text = "Network error, please try again"
                        self.emailErrorLabel.hidden = false
                    })
                } else {
                    let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                    
                    dispatch_async(dispatch_get_main_queue(), {
                        if let userId = jsonResult["user_id"] as? String {
                            // have a new userId save it and go to the game
                            
                            let defaults = NSUserDefaults.standardUserDefaults()
                            defaults.setValue(userId, forKey: "userId")
                            defaults.synchronize()
                            
                            var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController
                            self.presentViewController(next, animated: true, completion: nil)
                            
                        } else if let jsonErrors = jsonResult["errors"] as? NSDictionary {
                            if let userError = jsonErrors["username"] as? String {
                                self.usernameErrorLabel.text = userError
                                self.usernameErrorLabel.hidden = false
                                hasError = true
                            }
                            
                            if let emailError = jsonErrors["email"] as? String {
                                self.emailErrorLabel.text = emailError
                                self.emailErrorLabel.hidden = false
                                hasError = true
                            }
                            
                            if let passwdError = jsonErrors["password"] as? String {
                                self.passwordErrorLabel.text = passwdError
                                self.passwordErrorLabel.hidden = false
                                hasError = true
                            }
                        }
                    })
                }
                
            })
        }

if (!hasError){

// lets talk to the server

var url : String = "http://billion.lepunk.co.uk/api/"

var request : NSMutableURLRequest = NSMutableURLRequest()

var bodyData = "method=register&username=\(username)&email=\(email)&password=\(passwd)&facebook_id=\(facebookId)"

request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);

request.URL = NSURL(string: url)

request.HTTPMethod = "POST"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in

var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil

var statusCode = 0

if let httpResponse = response as? NSHTTPURLResponse {

statusCode = httpResponse.statusCode

}

if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){

dispatch_async(dispatch_get_main_queue(), {

self.emailErrorLabel.text = "Network error, please try again"

self.emailErrorLabel.hidden = false

})

} else {

let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

dispatch_async(dispatch_get_main_queue(), {

if let userId = jsonResult["user_id"] as? String {

// have a new userId save it and go to the game

let defaults = NSUserDefaults.standardUserDefaults()

defaults.setValue(userId, forKey: "userId")

defaults.synchronize()

var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController

self.presentViewController(next, animated: true, completion: nil)

} else if let jsonErrors = jsonResult["errors"] as? NSDictionary {

if let userError = jsonErrors["username"] as? String {

self.usernameErrorLabel.text = userError

self.usernameErrorLabel.hidden = false

hasError = true

}

if let emailError = jsonErrors["email"] as? String {

self.emailErrorLabel.text = emailError

self.emailErrorLabel.hidden = false

hasError = true

}

if let passwdError = jsonErrors["password"] as? String {

self.passwordErrorLabel.text = passwdError

self.passwordErrorLabel.hidden = false

hasError = true

}

})

}

})

}

Basically doing an async request to the API’s register method. If the request comes back with some errors display them otherwise grab the user id and chuck it in the App’s NSUserDefaults.standardUserDefaults storage (I will probably need to update this to be CoreData in the future) and redirect the user to the play area.

When the user decides to sign up with Facebook instead of the form there are two cases:

The user already registered (probably on a different device), in which case we need to redirect them to the play area
The user is not yet registered, so we need to ask them to set up a password

Here is the code that does that:

    func populateUserData() {
        self.facebookLoginLabel.hidden = false
        
        let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)
        graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in
            
            if ((error) != nil) {
                // Process error
            } else {
                
                let facebookId : String = result.valueForKey("id") as! String
                var url : String = "http://billion.lepunk.co.uk/api/"
                var request : NSMutableURLRequest = NSMutableURLRequest()
                var bodyData = "method=facebookLogin&facebook_id=\(facebookId)"
                request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);
                request.URL = NSURL(string: url)
                request.HTTPMethod = "POST"
                
                NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
                    var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
                    
                    var statusCode = 0
                    if let httpResponse = response as? NSHTTPURLResponse {
                        statusCode = httpResponse.statusCode
                    }
                    
                    if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){
                        dispatch_async(dispatch_get_main_queue(), {
                            // TODO: handle error
                        })
                    } else {
                        let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                        
                        dispatch_async(dispatch_get_main_queue(), {
                            if let userId = jsonResult["user_id"] as? String {
                                // we have a user id
                                let defaults = NSUserDefaults.standardUserDefaults()
                                defaults.setValue(userId, forKey: "userId")
                                defaults.synchronize()
                                
                                var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController
                                self.presentViewController(next, animated: true, completion: nil)
                            } else {
                                // seems like a new user, redirect to registration screen
                                let userFullName : String = result.valueForKey("name") as! String
                                var stringlength = count(userFullName)
                                var ierror: NSError?
                                var regex:NSRegularExpression = NSRegularExpression(pattern: "([^a-zA-Z0-9_])", options: NSRegularExpressionOptions.CaseInsensitive, error: &ierror)!
                                var generatedUserName = regex.stringByReplacingMatchesInString(userFullName, options: nil, range: NSMakeRange(0, stringlength), withTemplate: "")
                                
                                self.usernameInput.text = generatedUserName
                                let userEmail : String = result.valueForKey("email") as! String
                                self.emailInput.text = userEmail
                                self.facebookIdInput.text = facebookId
                            }
                        })
                    }
                })
                
                // check if we already have this user
            }
        })
    }

func populateUserData() {

self.facebookLoginLabel.hidden = false

let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)

graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in

if ((error) != nil) {

// Process error

} else {

let facebookId : String = result.valueForKey("id") as! String

var url : String = "http://billion.lepunk.co.uk/api/"

var request : NSMutableURLRequest = NSMutableURLRequest()

var bodyData = "method=facebookLogin&facebook_id=\(facebookId)"

request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);

request.URL = NSURL(string: url)

request.HTTPMethod = "POST"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in

var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil

var statusCode = 0

if let httpResponse = response as? NSHTTPURLResponse {

statusCode = httpResponse.statusCode

}

if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){

dispatch_async(dispatch_get_main_queue(), {

// TODO: handle error

})

} else {

let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

dispatch_async(dispatch_get_main_queue(), {

if let userId = jsonResult["user_id"] as? String {

// we have a user id

let defaults = NSUserDefaults.standardUserDefaults()

defaults.setValue(userId, forKey: "userId")

defaults.synchronize()

var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController

self.presentViewController(next, animated: true, completion: nil)

} else {

// seems like a new user, redirect to registration screen

let userFullName : String = result.valueForKey("name") as! String

var stringlength = count(userFullName)

var ierror: NSError?

var regex:NSRegularExpression = NSRegularExpression(pattern: "([^a-zA-Z0-9_])", options: NSRegularExpressionOptions.CaseInsensitive, error: &ierror)!

var generatedUserName = regex.stringByReplacingMatchesInString(userFullName, options: nil, range: NSMakeRange(0, stringlength), withTemplate: "")

self.usernameInput.text = generatedUserName

let userEmail : String = result.valueForKey("email") as! String

self.emailInput.text = userEmail

self.facebookIdInput.text = facebookId

}

})

}

})

// check if we already have this user

}

})

}

So we have a valid Facebook session and we can do a /me Graph API call to get the user’s details (including their email, since we asked for that permission). We do an async request to our API’s facebookLogin method to check if the user is already registered with us. If not populate the register form with the user’s data and add the FB id to the hidden input field. If the user already registered chuck the user id into the storage and redirect to the play view.

The code for the login view is pretty much the same so I’m not gonna share it here. The only difference really is when the user signs in with Facebook but they are not yet registered instead of redirecting them to the play area I’m redirecting them to the register view.

But of course it would be really annoying if the user needed to log in each time they used the app so some modification is needed for my Home view. I’ve added two new methods to my HomeViewController:

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        self.checkLoggedUser()
    }
    
    func checkLoggedUser(){
        let defaults = NSUserDefaults.standardUserDefaults()
        
        if let userId = defaults.valueForKey("userId") as? String {
            // we have a logged userId redirect to the game
            
            var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController
            self.presentViewController(next, animated: true, completion: nil)
        }
    }

override func viewDidAppear(animated: Bool) {

super.viewDidAppear(animated)

self.checkLoggedUser()

}

func checkLoggedUser(){

let defaults = NSUserDefaults.standardUserDefaults()

if let userId = defaults.valueForKey("userId") as? String {

// we have a logged userId redirect to the game

var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController

self.presentViewController(next, animated: true, completion: nil)

}

So when viewDidAppear is called I’m checking the standardUserDefaults storage for the user id. If that is present I’m immediately redirecting the user to the Play view. One of the gotchas about this code is you can not use viewDidLoad for this. According to stackoverflow it is because if you do a redirect in viewDidLoad you can end up with two active views which is a big no-no. Every day I learn something.

For testing purposes I also added a button to my Me view to let the user log out. Here is the associated action:

    @IBAction func doLogout(sender: AnyObject) {
        let defaults = NSUserDefaults.standardUserDefaults()
        defaults.removeObjectForKey("userId")
        defaults.synchronize()
        
        var next = self.storyboard?.instantiateViewControllerWithIdentifier("homeView") as! UIViewController
        self.presentViewController(next, animated: true, completion: nil)
    }

@IBAction func doLogout(sender: AnyObject) {

let defaults = NSUserDefaults.standardUserDefaults()

defaults.removeObjectForKey("userId")

defaults.synchronize()

var next = self.storyboard?.instantiateViewControllerWithIdentifier("homeView") as! UIViewController

self.presentViewController(next, animated: true, completion: nil)

}

If the user hits the button I’m removing the user id from the local storage and redirect them to the Home view. Important to note that calling defaults.synchronize() is a must here. Apparently iOS does the synchronisation of this storage periodically so you could end up in a weird state.

So this is the full login / register flow. Wasn’t too hard but I’m glad I’m over with it since it wasn’t the most exciting task to do. One thing I still need to figure out is how to kill the Facebook connection with the app when the user hits the log out button.

Tomorrow I’m gonna work on the API for the gameplay. Minor setback is that I need to give back the MacBook Pro I’m currently working on and start using my Mac Mini which is slow as hell.

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May 25, 2015

Writing my first iPhone app – Day 3 – Validating forms is no fun in any language

Yesterday I was quite busy boxing up my apartment for next week’s move (fuck i hate moving) so relatively small progress on the app, but the login / registration screen is getting there

Created two new views, one for login and one for registration obviously and linked them to LoginViewController and RegisterViewController. Also renamed my home screen’s controller to be HomeViewController (very imaginative naming, I know)

The bottom buttons are there to switch views between register and login + I still have my “let me in” button for entering directly to the Play view for testing purposes (really need to add a TODO to remove that from the final product at some point). The code for switching the views looks like this

    @IBAction func registerButtonClick(sender: AnyObject) {
        var next = self.storyboard?.instantiateViewControllerWithIdentifier("registerView") as! RegisterViewController
        self.presentViewController(next, animated: true, completion: nil)
    }
    
    @IBAction func loginButtonClick(sender: AnyObject) {
        var next = self.storyboard?.instantiateViewControllerWithIdentifier("loginView") as! LoginViewController
        self.presentViewController(next, animated: true, completion: nil)
        
    }
    @IBAction func loginOverride(sender: AnyObject) {
        var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController
        self.presentViewController(next, animated: true, completion: nil)
    }

@IBAction func registerButtonClick(sender: AnyObject) {

var next = self.storyboard?.instantiateViewControllerWithIdentifier("registerView") as! RegisterViewController

self.presentViewController(next, animated: true, completion: nil)

}

@IBAction func loginButtonClick(sender: AnyObject) {

var next = self.storyboard?.instantiateViewControllerWithIdentifier("loginView") as! LoginViewController

self.presentViewController(next, animated: true, completion: nil)

}

@IBAction func loginOverride(sender: AnyObject) {

var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController

self.presentViewController(next, animated: true, completion: nil)

}

As for the login and registration code: Why is that that in any language the most boring and tedious thing to do is form validation? Wish someone would come up with a sure way of doing it. Anyway, the code for my register form looks like this. Fokin’ boring

    func isValidEmail(testStr:String) -> Bool {
        // println("validate calendar: \(testStr)")
        let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,8}"
        
        let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
        return emailTest.evaluateWithObject(testStr)
    }
    
    func isValidUsername(testStr:String) -> Bool {
        // println("validate calendar: \(testStr)")
        let userRegEx = "^[a-zA-Z_0-9]{5,}$"
        
        let userTest = NSPredicate(format:"SELF MATCHES %@", userRegEx)
        return userTest.evaluateWithObject(testStr)
    }
    
    @IBAction func doRegister(sender: AnyObject) {
        var email = self.emailInput.text
        var username = self.usernameInput.text
        var passwd = self.passwordInput.text
        var hasError = false
        
        if (email == "") {
            emailErrorLabel.text = "Please enter your email address"
            emailErrorLabel.hidden = false
            hasError = true
        } else if (!self.isValidEmail(email)){
            emailErrorLabel.text = "Invalid email address"
            emailErrorLabel.hidden = false
            hasError = true
        } else {
            emailErrorLabel.hidden = true
        }
        
        if (username == "") {
            usernameErrorLabel.text = "Please pick a username"
            usernameErrorLabel.hidden = false
            hasError = true
        } else if (count(username)30){
            usernameErrorLabel.text = "Username must be between 5 and 30 characters"
            usernameErrorLabel.hidden = false
            hasError = true
        } else if (!self.isValidUsername(username)){
            usernameErrorLabel.text = "Username can only contain alphanumeric characters"
            usernameErrorLabel.hidden = false
            hasError = true
        } else {
            usernameErrorLabel.hidden = true
        }
        
        if (passwd == "") {
            passwordErrorLabel.text = "Please pick a password"
            passwordErrorLabel.hidden = false
            hasError = true
        } else if (count(passwd)<5){             
            passwordErrorLabel.text = "Password must be at least 5 characters long"             
            passwordErrorLabel.hidden = false             
            hasError = true         
        } else {             
            passwordErrorLabel.hidden = true         
        }                  

        if (!hasError){             
            // lets talk to the server             
            var url : String = "http://localhost/register.php"             
            var request : NSMutableURLRequest = NSMutableURLRequest()             
            var bodyData = "username=\(username)&email=\(email)&password=\(passwd)"             
            request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);             
            request.URL = NSURL(string: url)             
            request.HTTPMethod = "POST"                          

            NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
                var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
                
                var statusCode = 0
                if let httpResponse = response as? NSHTTPURLResponse {
                    statusCode = httpResponse.statusCode
                }
                
                if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){
                    dispatch_async(dispatch_get_main_queue(), {
                        self.emailErrorLabel.text = "Network error, please try again"
                        self.emailErrorLabel.hidden = false
                    })
                } else {
                    let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                    
                    dispatch_async(dispatch_get_main_queue(), {
                        
                    })
                }
                
            })
        }
    }

func isValidEmail(testStr:String) -> Bool {

// println("validate calendar: \(testStr)")

let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,8}"

let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx)

return emailTest.evaluateWithObject(testStr)

}

func isValidUsername(testStr:String) -> Bool {

// println("validate calendar: \(testStr)")

let userRegEx = "^[a-zA-Z_0-9]{5,}$"

let userTest = NSPredicate(format:"SELF MATCHES %@", userRegEx)

return userTest.evaluateWithObject(testStr)

}

@IBAction func doRegister(sender: AnyObject) {

var email = self.emailInput.text

var username = self.usernameInput.text

var passwd = self.passwordInput.text

var hasError = false

if (email == "") {

emailErrorLabel.text = "Please enter your email address"

emailErrorLabel.hidden = false

hasError = true

} else if (!self.isValidEmail(email)){

emailErrorLabel.text = "Invalid email address"

emailErrorLabel.hidden = false

hasError = true

} else {

emailErrorLabel.hidden = true

}

if (username == "") {

usernameErrorLabel.text = "Please pick a username"

usernameErrorLabel.hidden = false

hasError = true

} else if (count(username)30){

usernameErrorLabel.text = "Username must be between 5 and 30 characters"

usernameErrorLabel.hidden = false

hasError = true

} else if (!self.isValidUsername(username)){

usernameErrorLabel.text = "Username can only contain alphanumeric characters"

usernameErrorLabel.hidden = false

hasError = true

} else {

usernameErrorLabel.hidden = true

}

if (passwd == "") {

passwordErrorLabel.text = "Please pick a password"

passwordErrorLabel.hidden = false

hasError = true

} else if (count(passwd)<5){

passwordErrorLabel.text = "Password must be at least 5 characters long"

passwordErrorLabel.hidden = false

hasError = true

} else {

passwordErrorLabel.hidden = true

}

if (!hasError){

// lets talk to the server

var url : String = "http://localhost/register.php"

var request : NSMutableURLRequest = NSMutableURLRequest()

var bodyData = "username=\(username)&email=\(email)&password=\(passwd)"

request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);

request.URL = NSURL(string: url)

request.HTTPMethod = "POST"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in

var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil

var statusCode = 0

if let httpResponse = response as? NSHTTPURLResponse {

statusCode = httpResponse.statusCode

}

if (data == nil || error != nil || statusCode >= 400 || statusCode < 200){

dispatch_async(dispatch_get_main_queue(), {

self.emailErrorLabel.text = "Network error, please try again"

self.emailErrorLabel.hidden = false

})

} else {

let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

dispatch_async(dispatch_get_main_queue(), {

})

}

})

}

Couldn’t find any built in methods to validate emails so had to use regex (and not a very good one) to validate it on the front end. Obviously will need to do the same on the server side as well. The code I think is pretty self-explanatory. Checking for certain field values and displaying error messages depending on what rules they break. If no error detected do an async request to the server and check it’s response. Since the API is not yet ready I’m currently only checking for valid status.

I also implemented (partially) Facebook connect which was surprisingly easy. Since I couldn’t find a straight forward step by step guide to implement it in Swift here it is for you:

Install the Facebook SDK to your project using this guide
The guide tells you to set up a new Facebook App. The setup requires a valid App Store ID which you might not have. To trick it I just used a random app’s ID. To get the id you just copy any app’s url and get the relatively long number from the end of the link.
Add the SDK to your building targets. Click on the top element in your file manager in Xcode and open the Build Phases tab. Then in the “Link Binary with Libraries” section add the following three frameworks: FBSDKLoginKit, Bolts, FBSDKCoreKit
The SDK is written in Objective-C so you need to create a “bridging header” to use it in Swift. To do so create a “Bridging-Header.h” file in your project’s main folder with the following content:

C

#import <FBSDKCoreKit/FBSDKCoreKit.h> #import <FBSDKLoginKit/FBSDKLoginKit.h>

1
2

#import <FBSDKCoreKit/FBSDKCoreKit.h>
#import <FBSDKLoginKit/FBSDKLoginKit.h>
Click on the top element in your file browser and select “Build settings”. Make sure “All” is selected in the top menu. Scroll down to “Swift compiler – Code generation” and add “YourProjectname/Bridging-Header.h” as the “Objective-C bridging header”
Try building the project to make sure everything is linked correctly.

Using the Facebook SDK to implement FB Login is straight forward. First of all you need to modify your view class definition a bit.

class RegisterViewController: UIViewController, FBSDKLoginButtonDelegate {

1	class RegisterViewController: UIViewController, FBSDKLoginButtonDelegate {

When you do this you will see that Xcode will show you some errors. It is because your class is not yet comforming to FBSDKLoginButtonDelegate. To do that you need to add two new methods:

    func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) {
        println("User Logged In")
        
        if ((error) != nil){
            // Process error
        } else if result.isCancelled {
            // Handle cancellations
        } else {
            // If you ask for multiple permissions at once, you
            // should check if specific permissions missing
            if result.grantedPermissions.contains("email") {
                self.returnUserData()
                // Do work
            }
        }
    }
    
    func loginButtonDidLogOut(loginButton: FBSDKLoginButton!) {
        println("User Logged Out")
    }

func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) {

println("User Logged In")

if ((error) != nil){

// Process error

} else if result.isCancelled {

// Handle cancellations

} else {

// If you ask for multiple permissions at once, you

// should check if specific permissions missing

if result.grantedPermissions.contains("email") {

self.returnUserData()

// Do work

}

func loginButtonDidLogOut(loginButton: FBSDKLoginButton!) {

println("User Logged Out")

}

Right. The only thing left to do is to display the button. For this let’s modify the viewDidLoad method

    override func viewDidLoad() {
        super.viewDidLoad()
        if (FBSDKAccessToken.currentAccessToken() != nil){
            // User is already logged in, do work such as go to next view controller.
            self.returnUserData()
            let loginView : FBSDKLoginButton = FBSDKLoginButton()
            self.view.addSubview(loginView)
            loginView.center = self.view.center
            loginView.readPermissions = ["public_profile", "email", "user_friends"]
            loginView.delegate = self
            
        } else {
            let loginView : FBSDKLoginButton = FBSDKLoginButton()
            self.view.addSubview(loginView)
            loginView.center = self.view.center
            loginView.readPermissions = ["public_profile", "email", "user_friends"]
            loginView.delegate = self
        }
    }

    func returnUserData() {
        let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)
        graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in
            
            if ((error) != nil) {
                // Process error
                println("Error: \(error)")
            } else {
                println("fetched user: \(result)")
                let userName : NSString = result.valueForKey("name") as! NSString
                println("User Name is: \(userName)")
                let userEmail : NSString = result.valueForKey("email") as! NSString
                println("User Email is: \(userEmail)")
            }
        })
    }

override func viewDidLoad() {

super.viewDidLoad()

if (FBSDKAccessToken.currentAccessToken() != nil){

// User is already logged in, do work such as go to next view controller.

self.returnUserData()

let loginView : FBSDKLoginButton = FBSDKLoginButton()

self.view.addSubview(loginView)

loginView.center = self.view.center

loginView.readPermissions = ["public_profile", "email", "user_friends"]

loginView.delegate = self

} else {

let loginView : FBSDKLoginButton = FBSDKLoginButton()

self.view.addSubview(loginView)

loginView.center = self.view.center

loginView.readPermissions = ["public_profile", "email", "user_friends"]

loginView.delegate = self

}

func returnUserData() {

let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)

graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in

if ((error) != nil) {

// Process error

println("Error: \(error)")

} else {

println("fetched user: \(result)")

let userName : NSString = result.valueForKey("name") as! NSString

println("User Name is: \(userName)")

let userEmail : NSString = result.valueForKey("email") as! NSString

println("User Email is: \(userEmail)")

}

})

}

This code basically adds a new subview to the current view, which contains the login button. At this point I have literally no idea how to style the button itself. It just shows up right in the middle of the screen, which is currently fine with my crappy interface but I can see it being a pain in the future. This is how it looks atm:

So thats it for today. Tomorrow I’m gonna try and create the server side API and hook up those forms / FB login button. Happy bank holiday Monday everyone

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May 24, 2015

Writing my first iPhone app – Day 2

I have to say so far I’m liking Swift a lot. It is a nice, straight forward language with some awesome feature like conditionals.

Ok so what I did today? (well yesterday, but whatever)

First of all I added some new views to my interface. I realized that i will need to record the user’s activity on the server so I will need some sort of identifier to them. Of course I could just use the device’s ID but its better to make them create an account and use their login name / user id as the identifier. Anyway, I needed to add a login view as the first responder of my app. For now I will just add a simple button to redirect the flow to the “play” view, will deal with the actual registration later. Also added a new view to my tab controller for editing the user profile / view activity. Here is how my storyboard looks like at the moment:

The code for my LoginViewController is really just a placeholder now

import UIKit

class LoginViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    @IBAction func loginOverride(sender: AnyObject) {
        var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController
        self.presentViewController(next, animated: true, completion: nil)
    }
    
}

import UIKit

class LoginViewController: UIViewController {

override func viewDidLoad() {

super.viewDidLoad()

// Do any additional setup after loading the view, typically from a nib.

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

@IBAction func loginOverride(sender: AnyObject) {

var next = self.storyboard?.instantiateViewControllerWithIdentifier("tabController") as! UITabBarController

self.presentViewController(next, animated: true, completion: nil)

}

loginOverride just redirects the user to my tabController where the game code kicks off.

Made some good progress with the game itself as well. Actually pretty much the whole game logic is done. I did set up a fake API for getting the questions. Here is the not so interesting PHP code

$data = array( 
        "question" =>  "Mi az: 2 fule van megsem szatyor?",
        "answers" => array(
                "Szatyor",
                "Nyul bazdmeg",
                "Apad",
                "Makosbukta"
        ),
        "correct" => 1,
        "current_pos" => 1000000000
);

header("Content-type: application/json");
print(json_encode($data));

$data = array(

"question" => "Mi az: 2 fule van megsem szatyor?",

"answers" => array(

"Szatyor",

"Nyul bazdmeg",

"Apad",

"Makosbukta"

"correct" => 1,

"current_pos" => 1000000000

);

header("Content-type: application/json");

print(json_encode($data));

Turns out implementing async requests in Swift is fairly simple. Just have to call NSURLConnection.sendAsynchronousRequest and parse the response.

    func loadQuestion() {
        self.hideQuestion()
        
        var url : String = "http://localhost/stub.php"
        var request : NSMutableURLRequest = NSMutableURLRequest()
        request.URL = NSURL(string: url)
        request.HTTPMethod = "GET"
        
        NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) ->; Void in
            var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
            
            if (data == nil || error != nil){
                dispatch_async(dispatch_get_main_queue(), {
                    self.loadingLabel.text = "Network error"
                })
            } else {
                let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                
                dispatch_async(dispatch_get_main_queue(), {
                    self.renderQuestion(jsonResult)
                })
            }
            
        })
    }

func loadQuestion() {

self.hideQuestion()

var url : String = "http://localhost/stub.php"

var request : NSMutableURLRequest = NSMutableURLRequest()

request.URL = NSURL(string: url)

request.HTTPMethod = "GET"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) ->; Void in

var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil

if (data == nil || error != nil){

dispatch_async(dispatch_get_main_queue(), {

self.loadingLabel.text = "Network error"

})

} else {

let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

dispatch_async(dispatch_get_main_queue(), {

self.renderQuestion(jsonResult)

})

}

})

}

One thing I’ve learned about this and it is very important: never ever (EVER) try to update UI elements directly from the async request’s callback because it won’t take effect. It took me like half an hour to recognize that my code in fact works, but the UI elements are not updated. Clever people on stackoverflow told me that I should use dispatch_async to with dispatch_get_main_queue() to tell the main execution thread to update the UI.

As for rendering the question, it is pretty straight forward:

    func renderQuestion(jsonResult: NSDictionary!){
        let question = jsonResult["question"] as? String
        let answers = jsonResult["answers"] as! [String]
        self.currentCorrectAnswer = jsonResult["correct"] as! Int
            
        self.loadingLabel.hidden = true
            
        self.questionLabel.text = question
        self.questionLabel.hidden = false
            
        self.answer1Button.setTitle(answers[0], forState: UIControlState.Normal)
        self.answer1Button.hidden = false
            
        self.answer2Button.setTitle(answers[1], forState: UIControlState.Normal)
        self.answer2Button.hidden = false
            
        self.answer3Button.setTitle(answers[2], forState: UIControlState.Normal)
        self.answer3Button.hidden = false
            
        self.answer4Button.setTitle(answers[3], forState: UIControlState.Normal)
        self.answer4Button.hidden = false
            
        self.countDownTimerLabel.hidden = false
            
        self.startCountDown()
    }

func renderQuestion(jsonResult: NSDictionary!){

let question = jsonResult["question"] as? String

let answers = jsonResult["answers"] as! [String]

self.currentCorrectAnswer = jsonResult["correct"] as! Int

self.loadingLabel.hidden = true

self.questionLabel.text = question

self.questionLabel.hidden = false

self.answer1Button.setTitle(answers[0], forState: UIControlState.Normal)

self.answer1Button.hidden = false

self.answer2Button.setTitle(answers[1], forState: UIControlState.Normal)

self.answer2Button.hidden = false

self.answer3Button.setTitle(answers[2], forState: UIControlState.Normal)

self.answer3Button.hidden = false

self.answer4Button.setTitle(answers[3], forState: UIControlState.Normal)

self.answer4Button.hidden = false

self.countDownTimerLabel.hidden = false

self.startCountDown()

}

I want to allow the user 30 seconds to answer each question. I really hoped that the SDK has some sort of built in timer object, otherwise I should have implemented my own recursive async thing which I really didn’t want to do. Fortunately the SDK in fact has an NSTimer class so implementing the countdown was easy:

    var seconds = 30
    var timer = NSTimer()

    func subtractTime(){
        self.seconds--
        countDownTimerLabel.text = "\(self.seconds)s"
        
        if (self.seconds == 0) {
            self.timer.invalidate()
            countDownTimerLabel.text = "Out of time"
            countDownTimerLabel.textColor = UIColor.redColor()
            countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)
            nextQuestionButton.hidden = false
        }
    }
    
    func startCountDown(){
        self.seconds = 30
        countDownTimerLabel.text = "\(self.seconds)s"
        countDownTimerLabel.textColor = UIColor.darkGrayColor()
        countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 74)
        
        self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("subtractTime"), userInfo: nil, repeats: true)
        
    }

var seconds = 30

var timer = NSTimer()

func subtractTime(){

self.seconds--

countDownTimerLabel.text = "\(self.seconds)s"

if (self.seconds == 0) {

self.timer.invalidate()

countDownTimerLabel.text = "Out of time"

countDownTimerLabel.textColor = UIColor.redColor()

countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)

nextQuestionButton.hidden = false

}

func startCountDown(){

self.seconds = 30

countDownTimerLabel.text = "\(self.seconds)s"

countDownTimerLabel.textColor = UIColor.darkGrayColor()

countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 74)

self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("subtractTime"), userInfo: nil, repeats: true)

}

The only thing left to do is to hook up the answer buttons and check if the answer is correct. I simply added a tag to each button 0,1,2,3 and linked the touch up event to a new custom action:

    func wrongAnswer(){
        self.timer.invalidate()
        countDownTimerLabel.text = "Wrong"
        countDownTimerLabel.textColor = UIColor.redColor()
        countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)
        nextQuestionButton.hidden = false
    }
    
    func rightAnswer(){
        self.timer.invalidate()
        countDownTimerLabel.text = "Correct"
        countDownTimerLabel.textColor = UIColor.greenColor()
        countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)
        nextQuestionButton.hidden = false
    }
    
    @IBAction func sendAnswer(sender: AnyObject) {
        let buttonIndex = sender.tag
        
        if (buttonIndex == self.currentCorrectAnswer){
            self.rightAnswer()
        } else {
            self.wrongAnswer()
        }
    }

func wrongAnswer(){

self.timer.invalidate()

countDownTimerLabel.text = "Wrong"

countDownTimerLabel.textColor = UIColor.redColor()

countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)

nextQuestionButton.hidden = false

}

func rightAnswer(){

self.timer.invalidate()

countDownTimerLabel.text = "Correct"

countDownTimerLabel.textColor = UIColor.greenColor()

countDownTimerLabel.font = UIFont(name: countDownTimerLabel.font.fontName, size: 32)

nextQuestionButton.hidden = false

}

@IBAction func sendAnswer(sender: AnyObject) {

let buttonIndex = sender.tag

if (buttonIndex == self.currentCorrectAnswer){

self.rightAnswer()

} else {

self.wrongAnswer()

}

Simples. If the clicked button’s tag equals to the one got from the (fake) API display a big green message, otherwise a red one. In the future the app will report the result to the server for logging purposes and of course to move the player on the global board but that is for the future.

Tomorrow I’m gonna start building the server side a little bit and try to make the registration / login view and hopefully add Facebook login too

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May 23, 2015

Writing my first iPhone app – Day 1

So I decided to step a little bit out of my comfort zone professionally and try myself outside the scope of web development. I took a beginner course on Udemy about developing iPhone apps using Swift, but up until today I didn’t write a single line of Swift code. I hereby challenge myself to write my first app in 14 days. Now the app itself most probably won’t be ready for the app store straight away since I’m mostly focusing on functionality and not usability / design but it will be a good learning experience for me.

The app: The app will be a very simple game. Imagine a massive, 1 billion step board game with one single player. Everyone who is using the app will move the same player by answering trivia questions. If a given user answers the question correctly the player moves forward 1 step, otherwise it moves backwards one. I know, not the most original idea but it really is just for learning.

So here is what I did today (keep in mind I have literally no idea what I’m doing so probably I’m doing it all wrong)

I started off building a basic interface. What really surprised me, coming from web development, is how un-intuitive xcode’s interface (storyboard) builder is when it comes to “responsive” design. It took me ages to figure out how to make a single button stretch when I switch the emulator from iPhone 5s mode to iPhone 6. Basically you have to define the relative distance between the elements and the main view and the buttons will stretch to fill the space. I mean it kinda makes sense but how hard would it be for to allow defining sizes in %? Anyway my lame interface looks like this at the moment:

I know, it looks fugly but it renders properly in the simulator (still fugly but at least symmetric)

I can’t believe I spent like 3 hours on this, but at least I learnt something. Besides the interface I defined my outlets and set up a base controller which will handle my interaction with the (so far non-existent API) and update the interface elements as needed.

It really is a frustrating yet very fulfilling experience to code for iOS. I mean it is one thing to switch from PHP to Python but it is completely different when you are switching from web dev to desktop / mobile dev. I think the last time I had to deal with pointers and complex types was when I was like 14 coding in Borland Pascal.

Tomorrow I’m gonna hook up my class with a stub API and do some actual work on the logic. Will keep you posted (not like anyone is reading this)

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January 28, 2013

Facebook Hacker Cup 2013: My solutions

Task 1: Beautiful strings

When John was a little kid he didn’t have much to do. There was no internet, no Facebook, and no programs to hack on. So he did the only thing he could… he evaluated the beauty of strings in a quest to discover the most beautiful string in the world.

Given a string s, little Johnny defined the beauty of the string as the sum of the beauty of the letters in it.

The beauty of each letter is an integer between 1 and 26, inclusive, and no two letters have the same beauty. Johnny doesn’t care about whether letters are uppercase or lowercase, so that doesn’t affect the beauty of a letter. (Uppercase ‘F’ is exactly as beautiful as lowercase ‘f’, for example.)

You’re a student writing a report on the youth of this famous hacker. You found the string that Johnny considered most beautiful. What is the maximum possible beauty of this string?

Input
The input file consists of a single integer m followed by m lines.

Output
Your output should consist of, for each test case, a line containing the string “Case #x: y” where x is the case number (with 1 being the first case in the input file, 2 being the second, etc.) and y is the maximum beauty for that test case.

Constraints
5 ≤ m ≤ 50
2 ≤ length of s ≤ 500

My solution for this problem was fairly straight forward. Not the fastest solution I guess, but it works: get the string, count the unique alpha characters in it and add up the “beauty”

<?php

$content = file_get_contents("input.txt");
$content = preg_replace("/\r\n/i","\n",$content);
$rows = explode("\n",$content);
$row_count = $rows[0];

if (!is_numeric($row_count)){
	print("invalid input\n");
	exit();
}

$handle = fopen("output.txt","w+");

for($case=1;$case<=$row_count;$case++){
	$row = $rows[$case];
	$row = strtolower(preg_replace("/[^a-zA-Z]/i","",$row));
	
	if (!strlen($row)){
		print("Case #$case: 0\n");
		fwrite($handle,"Case #$case: 0\n");
		continue;
	}
	
	$letters = array();
	for($j=0;$j<strlen($row);$j++){
		if (!isset($letters[$row[$j]])){
			$letters[$row[$j]] = 1;
		} else {
			$letters[$row[$j]]++;
		}
	}
	
	$total_beauty = 0;
	$current_beauty = 26;
	arsort($letters);
	foreach($letters as $letter => $count){
		$total_beauty+=$count*$current_beauty;
		$current_beauty--;
	}
	
	print("Case #$case: $total_beauty\n");
	fwrite($handle,"Case #$case: $total_beauty\n");
}

<?php

$content = file_get_contents("input.txt");

$content = preg_replace("/\r\n/i","\n",$content);

$rows = explode("\n",$content);

$row_count = $rows[0];

if (!is_numeric($row_count)){

print("invalid input\n");

exit();

}

$handle = fopen("output.txt","w+");

for($case=1;$case<=$row_count;$case++){

$row = $rows[$case];

$row = strtolower(preg_replace("/[^a-zA-Z]/i","",$row));

if (!strlen($row)){

print("Case #$case: 0\n");

fwrite($handle,"Case #$case: 0\n");

continue;

}

$letters = array();

for($j=0;$j<strlen($row);$j++){

if (!isset($letters[$row[$j]])){

$letters[$row[$j]] = 1;

} else {

$letters[$row[$j]]++;

}

$total_beauty = 0;

$current_beauty = 26;

arsort($letters);

foreach($letters as $letter => $count){

$total_beauty+=$count*$current_beauty;

$current_beauty--;

}

print("Case #$case: $total_beauty\n");

fwrite($handle,"Case #$case: $total_beauty\n");

}

Task 2: Balanced Smileys

Your friend John uses a lot of emoticons when you talk to him on Messenger. In addition to being a person who likes to express himself through emoticons, he hates unbalanced parenthesis so much that it makes him go

Sometimes he puts emoticons within parentheses, and you find it hard to tell if a parenthesis really is a parenthesis or part of an emoticon.

A message has balanced parentheses if it consists of one of the following:
– An empty string “”
– One or more of the following characters: ‘a’ to ‘z’, ‘ ‘ (a space) or ‘:’ (a colon)
– An open parenthesis ‘(‘, followed by a message with balanced parentheses, followed by a close parenthesis ‘)’.
– A message with balanced parentheses followed by another message with balanced parentheses.
– A smiley face “:)” or a frowny face “:(”

Write a program that determines if there is a way to interpret his message while leaving the parentheses balanced.
Input

The first line of the input contains a number T (1 ≤ T ≤ 50), the number of test cases.
The following T lines each contain a message of length s that you got from John.
Output

For each of the test cases numbered in order from 1 to T, output “Case #i: ” followed by a string stating whether or not it is possible that the message had balanced parentheses. If it is, the string should be “YES”, else it should be “NO” (all quotes for clarity only)
Constraints
1 ≤ length of s ≤ 100

I spent quite a lot of time, about 40 minutes on this one. I ended up with a recursive function which relies on a regular expression: “/($.*)(:$)?(:$)?($)/U”. This regex will match the parts of the string which are in brackets even if the parts are containing a smiley. Then it is just a loop for counting the opening and closing parentheses.

<?php

$content = file_get_contents("input.txt");
$content = preg_replace("/\r\n/i","\n",$content);
$rows = explode("\n",$content);
$row_count = $rows[0];

if (!is_numeric($row_count)){
	print("invalid input\n");
	exit();
}

function replace_once($haystack, $needle, $replacement){
	$pos = strpos($haystack, $needle);
	if ($pos !== false){
		return substr_replace($haystack, $replacement, $pos, strlen($needle));
	} else {
		return $haystack;
	}
}

function is_balanced($string){

	preg_match_all("/(\(.*)(:\))?(:\()?(\))/U", $string, $matches);
	
	if (count($matches) && count($matches[0])){
		$remaining = $string;
		foreach($matches[0] as $key => $val){
			$balanced = true;
			
			$remaining = replace_once($remaining, $val, "");
			
			$val = substr($val, 1, strlen($val)-2);
			$balanced = is_balanced($val);
			if (!$balanced){
				return false;
			}
		}
		
		return is_balanced($remaining);
	} else {
		
		$string = str_replace(array(":)",":("),array("",""), $string);
		$open = 0;
		for($i=0;$i<strlen($string);$i++){
			if ($string[$i] == ")"){
				if ($open > 0){
					$open--;
				} else {
					return false;
				}
			}
			
			if ($string[$i] == "("){
				$open++;
			}
		}
		
		if ($open == 0){
			return true;
		} else {
			return false;
		}
	}
	
}

$handle = fopen("output.txt","w+");

for($case=1;$case<=$row_count;$case++){
	$row = $rows[$case];
	
	if (is_balanced($row)){
		print("Case #$case: YES\n");
		fwrite($handle,"Case #$case: YES\n");
	} else {
		print("Case #$case: NO\n");
		fwrite($handle,"Case #$case: NO\n");
	}
}

fclose($handle);

<?php

$content = file_get_contents("input.txt");

$content = preg_replace("/\r\n/i","\n",$content);

$rows = explode("\n",$content);

$row_count = $rows[0];

if (!is_numeric($row_count)){

print("invalid input\n");

exit();

}

function replace_once($haystack, $needle, $replacement){

$pos = strpos($haystack, $needle);

if ($pos !== false){

return substr_replace($haystack, $replacement, $pos, strlen($needle));

} else {

return $haystack;

}

function is_balanced($string){

preg_match_all("/($.*)(:$)?(:$)?($)/U", $string, $matches);

if (count($matches) && count($matches[0])){

$remaining = $string;

foreach($matches[0] as $key => $val){

$balanced = true;

$remaining = replace_once($remaining, $val, "");

$val = substr($val, 1, strlen($val)-2);

$balanced = is_balanced($val);

if (!$balanced){

return false;

}

return is_balanced($remaining);

} else {

$string = str_replace(array(":)",":("),array("",""), $string);

$open = 0;

for($i=0;$i<strlen($string);$i++){

if ($string[$i] == ")"){

if ($open > 0){

$open--;

} else {

return false;

}

if ($string[$i] == "("){

$open++;

}

if ($open == 0){

return true;

} else {

return false;

}

$handle = fopen("output.txt","w+");

for($case=1;$case<=$row_count;$case++){

$row = $rows[$case];

if (is_balanced($row)){

print("Case #$case: YES\n");

fwrite($handle,"Case #$case: YES\n");

} else {

print("Case #$case: NO\n");

fwrite($handle,"Case #$case: NO\n");

}

fclose($handle);

Task 3: Find the min

After sending smileys, John decided to play with arrays. Did you know that hackers enjoy playing with arrays? John has a zero-based index array, m, which contains n non-negative integers. However, only the first k values of the array are known to him, and he wants to figure out the rest.

John knows the following: for each index i, where k <= i < n, m[i] is the minimum non-negative integer which is *not* contained in the previous *k* values of m. For example, if k = 3, n = 4 and the known values of m are [2, 3, 0], he can figure out that m[3] = 1. John is very busy making the world more open and connected, as such, he doesn't have time to figure out the rest of the array. It is your task to help him. Given the first k values of m, calculate the nth value of this array. (i.e. m[n - 1]). Because the values of n and k can be very large, we use a pseudo-random number generator to calculate the first k values of m. Given positive integers a, b, c and r, the known values of m can be calculated as follows: m[0] = a m[i] = (b * m[i - 1] + c) % r, 0 < i < k Input The first line contains an integer T (T <= 20), the number of test cases. This is followed by T test cases, consisting of 2 lines each. The first line of each test case contains 2 space separated integers, n, k (1 <= k <= 10^5, k < n <= 10^9). The second line of each test case contains 4 space separated integers a, b, c, r (0 <= a, b, c <= 10^9, 1 <= r <= 10^9). Output For each test case, output a single line containing the case number and the nth element of m.

Well, I failed this task. Not because my solution wasn’t working. It wasn’t fast enough in some cases. I considered seed (it is not my first time on the Hacker cup) and tested it with large arrays but I missed a case when my script fails. The key speed up was when I realized that the analyzed array slices are repeating. They are repeating after every Kth element, therefor:

if ($n > $k * 2){
	$n = $k + ($n % $k) -1;
}

if ($n > $k * 2){

$n = $k + ($n % $k) -1;

}

It gave me a huge speed up, but apparently not enough. I tried to run my script with the test cases provided by Facebook’s system and it didn’t finish in the 6 minutes limit even on the high-compute Amazon EC2 instances. Epic fail. Well next time. Anyway, my solution for task #3:

<?php

set_time_limit(0);
ini_set("memory_limit","2048M");

$content = file_get_contents("input.txt");
$content = preg_replace("/\r\n/i","\n",$content);
$rows = explode("\n",$content);
$task_count = $rows[0];

if (!is_numeric($task_count)){
	print("invalid input\n");
	exit();
}


for($case=0; $case < $task_count; $case++){

	$m = array();
	
	$tmp = explode(" ",$rows[1+$case*2]);
	
	$n = $tmp[0]; // count($m);
	$k = $tmp[1]; // known length

	$tmp = explode(" ",$rows[2+$case*2]);
	
	$a = $tmp[0];
	$b = $tmp[1];
	$c = $tmp[2];
	$r = $tmp[3];

	$m[0] = $a;

	for ($i=1; $i < $k; $i++){
		$m[$i] = ($b * $m[$i-1] + $c) % $r;
	}

	// reduce n
	if ($n > $k * 2){
		$n = $k + ($n % $k) -1;
	}
	
	print($k."\t".$n."\n");

	for($i=$k; $i<$n; $i++){
		
		$current_slice = array_slice($m, $i-$k, $k);

		asort($current_slice);
		$min = -1;
		while(true){

			if (empty($current_slice)){
				$min = $min+1;
				break;
			}

			$test = array_shift($current_slice);
			
			if ($test > $min+1){
				$min = $min+1;
				break;
			} else {
				$min = $test;
			}
		}
		
		$m[$i] = $min;
	}
	
	print("Case #".($case+1).": ".$min."\n");
	

}

<?php

set_time_limit(0);

ini_set("memory_limit","2048M");

$content = file_get_contents("input.txt");

$content = preg_replace("/\r\n/i","\n",$content);

$rows = explode("\n",$content);

$task_count = $rows[0];

if (!is_numeric($task_count)){

print("invalid input\n");

exit();

}

for($case=0; $case < $task_count; $case++){

$m = array();

$tmp = explode(" ",$rows[1+$case*2]);

$n = $tmp[0]; // count($m);

$k = $tmp[1]; // known length

$tmp = explode(" ",$rows[2+$case*2]);

$a = $tmp[0];

$b = $tmp[1];

$c = $tmp[2];

$r = $tmp[3];

$m[0] = $a;

for ($i=1; $i < $k; $i++){

$m[$i] = ($b * $m[$i-1] + $c) % $r;

}

// reduce n

if ($n > $k * 2){

$n = $k + ($n % $k) -1;

}

print($k."\t".$n."\n");

for($i=$k; $i<$n; $i++){

$current_slice = array_slice($m, $i-$k, $k);

asort($current_slice);

$min = -1;

while(true){

if (empty($current_slice)){

$min = $min+1;

break;

}

$test = array_shift($current_slice);

if ($test > $min+1){

$min = $min+1;

break;

} else {

$min = $test;

}

$m[$i] = $min;

}

print("Case #".($case+1).": ".$min."\n");

}

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January 9, 2013

PHP header(“location”); vulnerability

Every documentation and every code piece you can find about PHP’s header(“location: ….”); function recommends using die(); after the statement, but I never realized why until a couple of days ago. Most of the times I use die(); or exit(); after redirect statements, but for some reason I forgot to do so in one of my script. I learned the hard way why is it important: someone gained partial access to my site’s admin area. Turns out you can turn off redirects in your browser and in that case the rest of the script will execute without problems. Rookie mistake, I know, but I thought it’s worth sharing

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January 3, 2013

Some cool and little known PHP functions / features

register_shutdown_function
Recently I was building a PHP based load balancer for handling long running (video streams, sometimes up to 1 hour) processes. My biggest problem were if the user closed the page the load balancer had to react. This handy function is the best solution for the problem. Basically it calls the callback function when the script’s execution finishes or the user closes the browser window
scandir
If you are tired of using opendir, readdir and closedir, this function is for you
glob
Even better than scandir. It will only list the files matching the pattern passed in as an argument
CURLOPT_PROGRESSFUNCTION
This is a fairly new feature of the curl library. You can specify a callback function which will be executed every time a chunk of data comes back from the remote host. Usually I’m using it to create progress bars for long running curl processes
escapeshellcmd
I’m dealing with loads of user generated files in many different languages. As you may know the golden rule: “Users are idiots” so they put spaces, quotes and many many random characters in the file names. escapeshellcmd is a really handy function to escape a command before you call exec

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