Re: iOS 9: Adding CALayer to self.view.layer causes EXC_BAD_ACCESS
Re: iOS 9: Adding CALayer to self.view.layer causes EXC_BAD_ACCESS
- Subject: Re: iOS 9: Adding CALayer to self.view.layer causes EXC_BAD_ACCESS
- From: Doug Hill <email@hidden>
- Date: Tue, 06 Dec 2016 11:51:00 -0800
I've wondered about this before, but maybe some Objective-C runtime experts know.
Does writing directly to the ivar backing a property bypass the ARC features of the property. For example, will a strong property be retained if you write directly to the ivar?
If not, that's your problem.
Doug
> On Dec 6, 2016, at 11:44 AM, Carl Hoefs <email@hidden> wrote:
>
> I get the following crash in my iOS 9 app simply by adding a CALayer to the current view controller's self.view.layer and then dismissing the current view controller. Simplified code:
>
> @property (strong,nonatomic) CALayer *layer;
> . . .
> _layer = [[CALayer alloc] init];
> [_layer setDelegate: self];
> [self.view.layer addSublayer:_layer];
>
> Upon dismissing the VC:
>
> [self dismissViewControllerAnimated:YES completion:nil];
>
> The following exception occurs:
>
> (lldb) bt
> * thread #1: tid = 0x121bd, 0x22c2c68a libobjc.A.dylib`objc_retain + 10, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xb0000010)
> frame #0: 0x22c2c68a libobjc.A.dylib`objc_retain + 10
> frame #1: 0x27a2a22a UIKit`-[UIView(Hierarchy) subviews] + 330
> frame #2: 0x27b3e1ea UIKit`discardEngineRecursive + 118
> frame #3: 0x27a2fd06 UIKit`-[UIView dealloc] + 630
> frame #4: 0x2336cd98 CoreFoundation`-[__NSDictionaryM dealloc] + 132
> frame #5: 0x22c2cf8a libobjc.A.dylib`objc_object::sidetable_release(bool) + 150
> frame #6: 0x22c2d3cc libobjc.A.dylib`(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 388
> frame #7: 0x23363f30 CoreFoundation`_CFAutoreleasePoolPop + 16
> frame #8: 0x23415c56 CoreFoundation`__CFRunLoopRun + 1598
> frame #9: 0x233641c8 CoreFoundation`CFRunLoopRunSpecific + 516
> frame #10: 0x23363fbc CoreFoundation`CFRunLoopRunInMode + 108
> frame #11: 0x24980af8 GraphicsServices`GSEventRunModal + 160
> frame #12: 0x27a9c434 UIKit`UIApplicationMain + 144
> * frame #13: 0x001b655e ProteinFold`main(argc=1, argv=0x0043bbc8) + 122 at main.m:14
>
> If I remove the CALayer first before the -dismissViewControllerAnimated:completion:, it doesn't crash:
>
> [layer removeFromSuperlayer];
>
> Why do I need to explicitly remove my added CALayer before dismissing the VC? Note: If I declare layer as weak, the crash does not occur, but neither does the layer display onscreen.
> -Carl
>
>
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