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POMultiple Modal-view Transitions Crash App
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copied!<p>I would like to present multiple modal views in sequence (e.g. show confirmation page after selecting a picture from image picker). My problem is that the animation of dismissal and presenting in subsequent steps without delay always crashes the app with an <code>EXC_BAD_ACCESS</code>.</p> <p>I assume that the problem is that <code>CoreAnimation</code> does not distinguish between the two transitions and cannot detect properly whether the first one has ended or not.</p> <p>My work around so far is to introduce a 1 section delay which seems to solve the problem. However, I think that this makes the code a bit fragile. Is there another workaround?</p> <p>Is this a bug in UIKit and should I submit a bug report?</p> <p><b>Sample code</b></p> <p>Here is a simple case that reproduce the crash:</p> <ol> <li><p>Create a new View-based project with the following class as the implementation of the main controller</p></li> <li><p>Hit 'cancel' when image picker view is presented</p></li> </ol> <p>Expected behavior: the picker view is dismissed and presented again due to the subsequent call in <code>viewDidAppear</code>.</p> <p>Actual behavior: It crashes with the stack trace presented below.</p> <p>Code:</p> <pre><code> #import "SampleViewController.h" @implementation SampleViewController - (void)showModal { UIImagePickerController *picker = [[UIImagePickerController alloc] init]; [self presentModalViewController:picker animated:YES]; // [picker release]; } - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; [self showModal]; // this line crashes the app // the following works as desired // [self performSelector:@selector(showModal) withObject:nil afterDelay:1]; } @end </code></pre> <p>Crash Stack trace:</p> <pre> #0 0x30b43212 in -[UIWindowController transitionViewDidComplete:fromView:toView:] #1 0x3095828e in -[UITransitionView notifyDidCompleteTransition:] #2 0x3091af0d in -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] #3 0x3091ad7c in -[UIViewAnimationState animationDidStop:finished:] #4 0x00b54331 in run_animation_callbacks #5 0x00b54109 in CA::timer_callback #6 0x302454a0 in CFRunLoopRunSpecific #7 0x30244628 in CFRunLoopRunInMode #8 0x32044c31 in GSEventRunModal #9 0x32044cf6 in GSEventRun #10 0x309021ee in UIApplicationMain #11 0x00002794 in main at main.m:14 </pre>

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