iOS 9 Crashing in _prepareForCAFlush with EXC_BAD_ACCESS KERN_INVALID_ADDRESS

Question

With the release of iOS 9, we are seeing several crash reports for what appears to be a bug from Apple\'s side of things in iOS 9. This is happening across device types (iPh

Answer 1

We encountered the a crash with a similar stack trace, and after a long investigation we found out that it was related to an other crash; fixing that also fixed this, however I'm still unsure how the two crashes are related.

Here are the details about the other crash:

We had a function call in one of our methods like

AudioServicesAddSystemSoundCompletion(self.soundID,  
                                      [[NSRunLoop currentRunLoop] getCFRunLoop],  
                                      kCFRunLoopDefaultMode,  
                                      AudioServicesSystemSoundCompletion,  
                                      (void *)CFBridgingRetain(self)); 

where AudioServicesSystemSoundCompletion looked like

void AudioServicesSystemSoundCompletion(SystemSoundID ssID,  void *clientData) {  
     AudioServicesRemoveSystemSoundCompletion(ssID);  
     CFRelease(clientData);  
}

Executing that function call two or more times simultaneously caused the app to crash. We fixed this by passing NULL instead of (void *)CFBridgingRetain(self) and removing the CFRelease(clientData); line.

Since this fix we no longer see the '_prepareForCAFlush' crash anymore.

Also note that according to Crashlytics the device had very high memory usage each time the crash has reproduced.

Hope this helps!