Project Purple was the codename for iOS back when it was basically a skunkworks project within Apple.  This callback is basically just an event bridge between the `CoreFoundation` layer (ported from OS X) and the `UIKit` layer (the next-generation Cocoa framework).

* [&quot;How Project Purple Turned into the iPhone&quot;](http://allthingsd.com/20120803/apples-scott-forstall-on-how-project-purple-turned-into-the-iphone/)

Just one more piece of information on PurpleEventCallback.

It&#39;s part of Graphics Services. In the case, if you disassemble GraphicsServices framework, you will find the source code of this method.

I have a string that is built out of three parts. The word I want the string to be (changes), a seperating part (doesn&#39;t change) and the last part which changes. I want to delete the seperating part and the ending part. The seperating part is &quot; - &quot; so what I&#39;m wondering is if theres a way to delete everything after a certaint part of the string.

An example of this scenario would be if I wanted to turn this: &quot;Stack Overflow - A place to ask stuff&quot; into this: &quot;Stack Overflow&quot;. Any help is appreciated!

Delete everything after part of a string

How can I create a blank png UIImage in Objective C programmatically (let&#39;s say 36x36 px)?

Thanks :)

How to create a blank transparent png in Objective-C?

In the stack trace of my iPhone application, I see a call to something called `PurpleEventCallback`. I wasn&#39;t able to find any documentation for it. What is this?

![PurpleEventCallback][1]

  [1]: http://i.stack.imgur.com/x9uwi.png

What is PurpleEventCallback?

<p>In the stack trace of my iPhone application, I see a call to something called <code>PurpleEventCallback</code>. I wasn't able to find any documentation for it. What is this?</p>
<p><img src="http://i.stack.imgur.com/x9uwi.png" alt="PurpleEventCallback"></p>


I&#39;m using MGSplitViewController and I&#39;m using`shouldAutorotateToInterfaceOrientation` to control the size of the master view controller on rotation. 

It&#39;s all working fine on iOS 5 but on iOS 6 (both simulator and iPad) `shouldAutorotateToInterfaceOrientation` is never called.

Is this a bug that I should expect to be fixed with the final release of iOS 6 or something that I&#39;m not aware of has changed?

shouldAutorotateToInterfaceOrientation not being called in iOS 6

In Apple&#39;s AppStore Terms &amp; Conditions, you may find the following statement in relation to Auto-renewable In App Purchases:

&gt;&quot;Certain paid In App Subscriptions may offer a free trial period prior to charging your Account.&quot;

How does it work? I haven&#39;t seen any option to allow such free trial period for my Auto-renewable IAPs in iTunes Connect.

How to set-up In App Purchase free trial period in iOS app

Is it possible to control UIView border properties (color, thickness, etc...) directly from interface builder or I can only do it programmatically?

Is it possible to set UIView border properties from interface builder?

What is the ***iOS 6.0*** user agent string?

----------

Previous user-agent strings:

 - [**iOS 5.1** - What is the iOS 5.1 user agent string?][1]
 - [**iOS 5.0** - What is the iOS 5.0 user agent string?][2]
 - [**iOS 4.0** - What is the iPhone 4 user-agent?][3]


  [1]: https://stackoverflow.com/q/10152433/836407
  [2]: https://stackoverflow.com/q/7825873/836407
  [3]: https://stackoverflow.com/q/3105555/836407


What is the iOS 6 user agent string?

Suppose I have a nav controller stack with 2 view controllers: VC2 is on top and VC1 is underneath.  Is there code I can include in VC1 that will detect that VC2 has just been popped off the stack?  

Since I&#39;m trying to detect the popping of VC2 from within the code for VC1 it seems that something like **viewWillAppear** or **viewDidAppear** won&#39;t work, because those methods fire every time VC1 is displayed, including when it is first pushed on the stack.

**EDIT:** it seems I was not very clear with my original question.  Here&#39;s what I&#39;m trying to do: determine when VC1 is being shown due to VC2 being popped off the top of the stack.  Here&#39;s what I&#39;m NOT trying to do: determine when VC1 is being shown due to being pushed onto the top of the stack.  I need some way that will detect the first action but NOT the second action.  

Note: I don&#39;t particularly care about VC2, it can be any number of other VCs that get popped off the stack, what I do care about is when VC1 becomes the top of the stack again due to some other VC begin popped off the top.

iOS how to detect programmatically when top view controller is popped?

The new iPhone 5 display has a new aspect ratio and a new resolution (640 x 1136 pixels).

What is required to develop new or transition already existing applications to the new screen size?

What should we keep in mind to make applications &quot;universal&quot; for both the older displays and the new widescreen aspect ratio?


How to develop or migrate apps for iPhone 5 screen resolution?

&gt; **Possible Duplicate:**  
&gt; [How to develop or migrate apps for iPhone 5 screen resolution?](https://stackoverflow.com/questions/12395200/how-to-develop-or-migrate-apps-for-iphone-5-screen-resolution)  

&lt;!-- End of automatically inserted text --&gt;

I was just wondering with how should we deal with the iPhone 5 bigger screen size.

As it has more pixels in height, things like GCRectMake that use coordinates (and just doubled the pixels with the retina/non retina problem) won&#39;t work seamlessly between versions, as it happened when we got the [Retina][1].

And will we have to design two storyboards, just like for the iPad?

I personally don&#39;t think Apple will require you to check the screen size every time you have to draw something, like many answers say. Does that happen with the iPad? 

  [1]: http://en.wikipedia.org/wiki/Retina_Display


iOS 6 apps - how to deal with iPhone 5 screen size?

I have just installed Xcode 4.5 for iOS6 support, and I have seen a new icon called &#39;Exit&#39; in my Storyboard, listed under my view controllers along with &#39;First Responder&#39; etc. A little green icon labeled &#39;Exit&#39;.

I can find anything about it, nor work out how it can be used. How does it work?


Xcode 4.5 Storyboard &#39;Exit&#39;

I&#39;ve just upgraded to Xcode 4.5 GM and found out that you can now apply the &#39;4&quot; Retina&#39; size to your view controller in the storyboard.

Now if I want to create an application that runs on both iPhone 4 and 5, of course I have to build every window twice, but I also have to detect whether the user has an iPhone with 3.5&quot; or 4&quot; screen and then apply the view.

How should I do that?

How to detect iPhone 5 (widescreen devices)?

When I&#39;m validating my app I get this error: 

&gt; the application bundle does not contain an icon in ICNS format, containing both a `512x512` and a `512x512@2x` image.
 
I use to make the icns icons with [Img2icns][1] app and until today it always worked properly. But now I&#39;m getting that error and there&#39;s no way to make it work. I tried to put two PNG files together (`512x512` and `1024x1024`) in [Img2icns][2] but I always get that error. I also tried to follow the instructions in Apple&#39;s OS X Human Interface Guideline but when I try to make the icon sets I get this terminal error:

&gt; -bash: syntax error near unexpected token &#39;newline&#39;

I am not very good with terminal commands so maybe I&#39;m doing something wrong. I wrote:

    iconutil -c icns &lt;/Users/myname/SDK Mac Apps/MyApp/grafica/icon.iconset&gt;

If anyone could help it would be very much appreciated. Thanks, Massy.

  [1]: http://www.img2icnsapp.com/
  [2]: http://www.img2icnsapp.com/

How to manually create icns files using iconutil?

I upgraded [Xcode][1] version and when using external static libraries, I get this message:

&gt; ld: file is universal (3 slices) but does not contain a(n) armv7s slice: /file/location for architecture armv7s
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Is there any way to bypass this and add support to the library if the developer of the library hasn&#39;t updated their library yet?

  [1]: http://en.wikipedia.org/wiki/Xcode


File is universal (three slices), but it does not contain a(n) ARMv7-s slice error for static libraries on iOS, anyway to bypass?

I just installed a software update that I was prompted for, presumably affecting Xcode.  Now when I start Xcode, I am presented with a dialog box which states that Xcode must install the Mobile Device Framework before continuing.  When I try to do this, after providing my password, it fails with &quot;An unknown error occurred. See the install log for more details.&quot;  I do not see anything useful in install.log that identifies the problem.  I&#39;ve tried re-installing multiple times and rebooting to no avail.

I&#39;m currently running Xcode 4.3.  Perhaps I need to upgrade to 4.4?  Has anyone else run into this problem?

Error during Xcode Component Installation

As the `ShouldAutorotateToInterfaceOrientation` is deprecated in iOS 6 and I used that to force a particular view to **portrait only**, what is the correct way to do this in iOS 6?  This is only for one area of my app, all other views can rotate.

How to force a UIViewController to Portrait orientation in iOS 6

For example, I got a stack trace like this:

    java.lang.NullPointerException
	abc.investxa.presentation.controllers.UnixServerJobController.handleRequest(UnixServerJobController.java:66)
	org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:807)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:501)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

So what is the root cause of this exception?
From the stack trace, I found out that there is a problem with `doFilter` function in the `OncePerRequestFilter` class! However, when I put a break point there and the program never stop at that break point.

Could anyone give explanation about this!?
And in general case, how should I use that stack case for debugging (read from bottom to top or from top to bottom)!

How to read and understand the java stack trace?

It&#39;s clear why stack traces are affected with Microsoft&#39;s new programming paradigm. We now have a semantic stack and a couple of physical ones (my choice of words).

What I get to see is an exception&#39;s `StackTrace` property (and in the debugger) is the physical ones, concatenated:

    private async Task CheckFooAndBar()
    {
        var log = LogManager.GetLogger(&quot;Test&quot;);
        log.Info(&quot;CheckFooAndBar&quot;);
        try
        {
            await Foo();
        }
        catch (Exception ex)
        {
            log.Info(&quot;StackTrace of last exception: &quot; + ex.StackTrace);
        }
        Console.ReadKey();
    }
    private async Task Foo()
    {
        await Task.Factory.StartNew(() =&gt; Thread.Sleep(1000));
        await Bar();
        await Task.Factory.StartNew(() =&gt; Thread.Sleep(1000));
    }
    private async Task Bar()
    {
        await Task.Factory.StartNew(() =&gt; Thread.Sleep(1000));
        throw new Exception();
        await Task.Factory.StartNew(() =&gt; Thread.Sleep(1000));
    }

This gives:

    StackTrace of last exception:    at NLogAsyncExceptionTestCase.Program.&lt;Bar&gt;d__d.MoveNext() in c:\Users\Jens\Documents\Visual Studio 2012\Projects\NLogAsyncExceptionTestCase\NLogAsyncExceptionTestCase.Console\Program.cs:line 53
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
       at NLogAsyncExceptionTestCase.Program.&lt;Foo&gt;d__8.MoveNext() in c:\Users\Jens\Documents\Visual Studio 2012\Projects\NLogAsyncExceptionTestCase\NLogAsyncExceptionTestCase.Console\Program.cs:line 44
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
       at NLogAsyncExceptionTestCase.Program.&lt;CheckFooAndBar&gt;d__0.MoveNext() in c:\Users\Jens\Documents\Visual Studio 2012\Projects\NLogAsyncExceptionTestCase\NLogAsyncExceptionTestCase.Console\Program.cs:line 30 

My question is: Is there a (convenient, standard) way to convert this to a proper backtrace in the semantic sense, such as:

    CheckFooAndBar
    Foo
    Bar

Of course there could be a mixture of awaits and inline path fragments in the stack.

I tried looking at the stack as it is with .NET 4.5 and SL5 with the async targetting pack, but not yet with WinRT. The output is from .NET 4.5.

In SL5, which is what I mainly do, the situation is more problematic: You don&#39;t get line numbers in stack traces in Silverlight (even with elevated privileges), which makes the need for context more important.

Stack traces with async/await

There&#39;s a common problem I&#39;ve come across a few times when logging exceptions in Java. There seem to be various different types to deal with. E.g. some wrap other exceptions and some don&#39;t have a message at all - only a type.

Most code I&#39;ve seen logs an exception by using either `getMessage()` or `toString(`). But these methods don&#39;t always capture all the information needed to pinpoint the problem - other methods such as `getCause()` and `getStackTrace()` sometimes provide additional info.

For example, the exception I&#39;m looking at right now in my Eclipse Inspect window is an `InvocationTargetException`. The exception itself has no cause, no message, no stacktrace ... but the target from getCause() is `InvalidUseOfMatchersException`, with these details populated.

So my question is: Given an exception of *any* type as an input, please provide a single method that will output a nicely formatted string containing *all* relevant information about the Exception (e.g. possibly recursively calling `getCause()` amongst other things?) Before posting, I was nearly going to have a stab at it myself but really don&#39;t want to reinvent the wheel - surely such a thing must have been done many times before...?

*Please don&#39;t point me at any particular logging or utility framework to do this. I&#39;m looking for a fragment of code rather than a library since I don&#39;t have the right to add external dependencies on the project I&#39;m working on and it&#39;s actually being logged to part of a webpage rather than a file. If it&#39;s a case of copying the code fragment out of such a framework (and attributing it) that&#39;s fine :-)*

How to log as much information as possible for an exception in Java?

I have the following sample code setup in a WebApi application:

	[HttpGet]
	public double GetValueAction()
	{
		return this.GetValue().Result;
	}

	public async Task&lt;double&gt; GetValue()
	{
		return await this.GetValue2().ConfigureAwait(false);
	}

	public async Task&lt;double&gt; GetValue2()
	{
		throw new InvalidOperationException(&quot;Couldn&#39;t get value!&quot;);
	}

Sadly, when GetValueAction gets hit, the stack trace that comes back is:

        &quot; at MyProject.Controllers.ValuesController.&lt;GetValue2&gt;d__3.MoveNext() in c:\dev\MyProject\MyProject\Controllers\ValuesController.cs:line 61 --- End of stack trace from previous location where exception was thrown --- 
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
    at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
    at MyProject.Controllers.ValuesController.&lt;GetValue&gt;d__0.MoveNext() in c:\dev\MyProject\MyProject\Controllers\ValuesController.cs:line 56&quot;

Thus, I get (mangled) GetValue2 and GetValue in the trace, but no mention of GetValueAction. Am I doing something wrong? Is there another pattern that will get me more complete stack traces?

EDIT: my goal is not to write code relying on the stack trace, but instead to make failures in async methods easier to debug.

Is it possible to get a good stack trace with .NET async methods?

While debugging is there anyway to see a complete stack trace, list of methods called in main thread. Or any way to print them on command window.

Content Type	Original Author	Original Content on Stackoverflow
Question	Manav	View Question on Stackoverflow
Solution 1 - Ios	gavinb	View Answer on Stackoverflow
Solution 2 - Ios	Victor Ronin	View Answer on Stackoverflow

What is PurpleEventCallback?

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

How to create a blank transparent png in Objective-C?

Delete everything after part of a string

Attributions