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 <newsli...@autonomy.caltech.edu> > 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 > > > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/cocoadev%40breaqz.com > > This email sent to cocoa...@breaqz.com _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
