Vi Cheatsheet

a -> Append cursor (After position)
i -> Insert cursor (At position)
esc -> Remove cursor if active
:wq -> Save and quit
:q -> Ask to save and quit
:q! -> Quit without saving
dd -> Cut the line
yy -> Copy the line
p -> Paste the line
:n -> Go to line n
/text -> Search for ‘text’
n -> Jump to next match when search is active
0 -> Go to the beginning of the line
$ -> Go to the end of the line
G -> Go to the end of the document
yn + arrow down -> Copy the current line with next n lines
yn + arrow up -> Copy the current line with previous n lines

Gamification: http://vim-adventures.com (Even though it’s for vi not vim there shouldn’t be any major differences as mentioned here.)

Sample Apple Push Notification PHP Script

This is an old script that I used to use for sending notifications. I don’t remember the source, on the other hand, it has been modified a couple of times already.

Even though I could manage to send notifications with this script, the Apple server was rejecting the connection after the amount reaches more than 50. It was usually getting cut off around 70. So it needs to get some management for not sending in a loop, like threading or whatever.

<?php
 
// set time limit to zero in order to avoid timeout
set_time_limit(0);
 
// charset header for output
header('content-type: text/html; charset: utf-8');
 
// this is the pass phrase you defined when creating the key
$passphrase = 'my_secret_pass';
 
// you can post a variable to this string or edit the message here
if (!isset($_POST['msg'])) {
$_POST['msg'] = "Notification message here!";
}
 
// tr_to_utf function needed to fix the Turkish characters
$message = tr_to_utf($_POST['msg']);
 
// load your device ids to an array
$deviceIds = array(
'lh142lk3h1o2141p2y412d3yp1234y1p4y1d3j4u12p43131p4y1d3j4u12p4313',
'y1p4y1d3j4u12p43131p4y1d3j4u12p4313lh142lk3h1o2141p2y412d3yp1234'
);
 
// this is where you can customize your notification
$payload = '{"aps":{"alert":"' . $message . '","sound":"default"}}';
 
$result = 'Start' . '<br />';
 
////////////////////////////////////////////////////////////////////////////////
// start to create connection
$ctx = stream_context_create();
stream_context_set_option($ctx, 'ssl', 'local_cert', 'MyAppGenerated.pem');
stream_context_set_option($ctx, 'ssl', 'passphrase', $passphrase);
 
echo count($deviceIds) . ' devices will receive notifications.<br />';
 
foreach ($deviceIds as $item) {
    // wait for some time
    sleep(1);
     
    // Open a connection to the APNS server
    $fp = stream_socket_client('ssl://gateway.push.apple.com:2195', $err, $errstr, 60, STREAM_CLIENT_CONNECT | STREAM_CLIENT_PERSISTENT, $ctx);
 
    if (!$fp) {
        exit("Failed to connect: $err $errstr" . '<br />');
    } else {
        echo 'Apple service is online. ' . '<br />';
    }
 
    // Build the binary notification
    $msg = chr(0) . pack('n', 32) . pack('H*', $item) . pack('n', strlen($payload)) . $payload;
     
    // Send it to the server
    $result = fwrite($fp, $msg, strlen($msg));
     
    if (!$result) {
        echo 'Undelivered message count: ' . $item . '<br />';
    } else {
        echo 'Delivered message count: ' . $item . '<br />';
    }
 
    if ($fp) {
        fclose($fp);
        echo 'The connection has been closed by the client' . '<br />';
    }
}
 
echo count($deviceIds) . ' devices have received notifications.<br />';
 
// function for fixing Turkish characters
function tr_to_utf($text) {
    $text = trim($text);
    $search = array('Ü', 'Þ', 'Ð', 'Ç', 'Ý', 'Ö', 'ü', 'þ', 'ð', 'ç', 'ý', 'ö');
    $replace = array('Ãœ', 'Åž', '&#286;ž', 'Ç', 'Ä°', 'Ö', 'ü', 'ÅŸ', 'ÄŸ', 'ç', 'ı', 'ö');
    $new_text = str_replace($search, $replace, $text);
    return $new_text;
}
 
// set time limit back to a normal value
set_time_limit(30);

Use Sublime Text to Bulk Rename Your Files

There are two cool plugins: One is dired, which allows you to use Sublime Text to manage your files and folders; and another is Text Pastry, which helps you to put increasing numbers to the multi-selected cursors (Of course, it is more than that, just not in this case).

Go ahead and combine this two. Yes, giving numbered names to contents of a folder. There were (in fact, probably still are) utilities existed that people buy for. Why pay, when you can do it with plugins?

First, install dired and Text Pastry plugins from Sublime Text Package Control. No need to restart, just get into it directly by pressing Cmd+Shift+P -> dired: Goto Anywhere -> Goto Directory and then hit enter. It doesn’t matter what directory you are getting into since you can now navigate between folders thanks to dired.

Now, you can see the contents of the directory you are currently inside of, and you can see the shortcuts for navigation. Goto a directory that you want to bulk rename contents of and then press R. Now you can rename the files by using great abilities of Sublime Text such as locating matches, inserting multiple cursors and all.

bulk-rename-files-using-sublime-text-dired-and-text-pastry

Assume that you have a set of images that were taken during one of your trips and you want to rename them like -> trip_1.jpg, trip_2.jpg and so. You opened the folder in Sublime, selected all the images (lines), set all of the names to trip_.jpg and placed your multi cursors after _ (before .). Now what? Just hit Cmd+Shift+P again and then select Text Pastry: From 1 To X. That’s it. Now all of your files have numbers increased by 1 at the end of their names. Hit Ctrl+Enter to save changes and you’re good to go.

Important Note: Dired is no longer maintained so it will not appear on the package control. The developer was kind enough to share the latest working copy so I’ve uploaded it to Github. Install instructions can be found inside README.md. To download: https://github.com/kublaios/dired

DateTime Ticks With Objective-C

If you need to generate unique strings for every case, the concept of DateTime.Ticks is probably the best solution for you. It represents the count of seconds since the oldest DateTime object available.

However, DateTime.Ticks usage comes from .NET platform and it is that easy in .NET, not in Objective-C.

To generate a ticks number in Objective-C, you need to do the following:

  1. Create an NSDate (01.01.0001), I know, rocking.
  2. Calculate the ticks between this oldest date and [NSDate date] (which means now).
  3. Turn that double variable to an integer. Well, long integer. Or… long long integer. (True story).

Here’s how I did it:

// Create the date formatter
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyyMMdd"];
 
// Create the oldest day possible
NSDate *ticksDate = [dateFormat dateFromString:@"00010101"];
 
// Get ticks difference between now and 01.01.0001 in double   
double ticksDouble = [[NSDate date] timeIntervalSinceDate:ticksDate];
 
// Turn it to a long long int
long long int ticks = llround(ticksDouble);
 
// Test it
NSLog(@"%lli",ticks);

html2canvas- Take Screenshot of Web Page and Save It to Server (JavaScript and PHP)

FeedBack is important. Usually, end-users struggle to clarify their problems. And you might be unreachable for a phone call or remote connection.

That causes a huge need of visualization. First solution that appears in mind is to capture the current screen of user.

However, when I tried to implement that, it wasn’t so easy as I expected. Some old ways offer ActiveX but it seems too outdated. Since there’s a bridge needed between client side and server, JS libraries are the best way.

There’s a great library, html2canvas. It is told to be reverse-engineered version of Google Plus’ way of taking screenshots.

When I first discovered this library, it took me a while to use for simplest implementation. I just wanted to visualize a div element. However, there was no single page to tell the whole path to follow, thus I had to combine various sources.

Here’s how you can easily use for taking a screenshot of a div:

1- Import libraries
There are 3 libraries to import:

  • jquery.js
  • html2canvas.js
  • jquery.plugin.html2canvas.js

You can download html2canvas and html2canvas jQuery plugin from this link.
Note: The source link contains html2canvas v0.40. I recommend you to check for a newer version and use it instead from official html2canvas site.

I have used jquery.min.js v1.7.1 but you can try other versions. For this jQuery library, use this link.
Here’s first lines of code:

<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript" src="js/html2canvas.js"></script>
<script type="text/javascript" src="js/jquery.plugin.html2canvas.js"></script>

2- Create your div
In my code, I used html2canvas for a div. You can use the whole body tag instead, it’s up to you.
Attach a div element to the page with a certain id:

<div id="target">
<!-- Render your page inside of this div. -->
</div>

3- Create a button and a hidden form
This part is important. In order to save the image to server, we need to pass captured image data with a form field.
In 4th step, you’ll see JavaScript code that writes the image data to hidden field and posts the form.

<input type="submit" value="Take Screenshot Of Div" onclick="capture();" />
<form method="POST" enctype="multipart/form-data" action="save.php" id="myForm">
    <input type="hidden" name="img_val" id="img_val" value="" />
</form>

4- JavaScript Code

function capture() {
    $('#target').html2canvas({
        onrendered: function (canvas) {
            //Set hidden field's value to image data (base-64 string)
            $('#img_val').val(canvas.toDataURL("image/png"));
            //Submit the form manually
            document.getElementById("myForm").submit();
        }
    });
}

5- Use the posted values
Here I used a form to post the value. You can use Ajax calls or whatever. I have a PHP file, save.php. In this file, we will both show the picture and save it to the server.

//save.php code
 
//Show the image
echo '<img src="'.$_POST['img_val'].'" />';
 
//Get the base-64 string from data
$filteredData=substr($_POST['img_val'], strpos($_POST['img_val'], ",")+1);
 
//Decode the string
$unencodedData=base64_decode($filteredData);
 
//Save the image
file_put_contents('img.png', $unencodedData);

6- Enjoy your day
So that’s pretty much it. You can download the codes from Github repository page.

7- Notes

* This tutorial uses html2canvas v0.4.0 – 30.1.2013. It has a new release, v0.4.1 – 7.9.2013, can be downloaded from here. Though avaliability of newer versions haven’t been tested with the code above.

* Some people have declared that they had issues with checkbox/radiobutton states on the captured image. Stu has shared his code to capture these elements with their states. I haven’t tried by myself but people who face problem about this may get some opinion from his comment.