Aligning SKPhysicsBody Correctly with SKShapeNode

When you want to create a circle in SpriteKit, SKShapeNode is the quickest and the simplest way for it. You don’t need to create images, you can manage the size, fill colour, stroke colours etc.

However, if you want this node to involve with collisions, you may get some trouble when creating an SKPhysicsBody for that node. The creating process is similar to SKSpriteNode but the alignment of it is different.

By default, SKShapeNode anchor points begin from (0, 0) and there isn’t any property to set it as we want. When we assign a SKPhysicsBody to this node, body’s anchor is its center point so the body doesn’t cover the node correctly.

Here’s how it looks when you want to implement for SKShapeNode as you do in SKSpriteNode:

skshapenode-skphysicsbody

There are plenty of people who were unable to solve this issue. Yet there is one answer on SO that helped me out with this.

To work around this situation, you can create an SKSpriteNode to implement the body and an SKShapeNode as the SKSpriteNode’s child to draw the shape.

First, create an SKSpriteNode and set the width and height same with the diameter of the circle

float radius = 30.0;
SKSpriteNode *aCircle = [SKSpriteNode spriteNodeWithColor:[UIColor clearColor] size:CGSizeMake(radius * 2, radius * 2)];
//

Then create a circular SKPhysicsBody for the SKSpriteNode (thankfully, this is possible)

SKPhysicsBody *circleBody = [SKPhysicsBody bodyWithCircleOfRadius:radius];
[circleBody setDynamic:NO];
[circleBody setUsesPreciseCollisionDetection:YES];
[aCircle circleBody];
//

Here is the key part. Create a CGPathRef as an ellipse in the rect with correct center values.

CGPathRef bodyPath = CGPathCreateWithEllipseInRect(CGRectMake(-[aCircle size].width / 2, -[aCircle size].height / 2, [aCircle size].width, [aCircle size].width), nil);
SKShapeNode *circleShape = [SKShapeNode node];
[circleShape setFillColor:[UIColor redColor]];
[circleShape setLineWidth:0];
[circleShape setPath:bodyPath];
[aCircle addChild:circleShape];
CGPathRelease(bodyPath);
//

Don’t forget to add the child to the scene then you are done. As you can see below, the physics body now matches the node frame correctly.

skspritenode-skshapenode-skphysicsbody.png

Source link of the answer:
SKPhysicsBody not as expected

Other questions about similar issues:
How to align SKPhysicsBody and SKShapeNode?
Align SKPhysicsBody with SKShapeNode
SKPhysicsBody does not work on SKShapeNode
SKshapenode is not responding to Physicsbody
how to make collisions with skshapenode circles
Keeping an SKShapeNode within the bounds of an SKSpriteNode

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);