Crash When Removing Self as Observer - CALayer

I am having a crash in my CALayer subclass when I remove myself as an observer in -(void)dealloc:

- (void)dealloc {
 [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
 [colorLabel release];
 [_color release];
 [super dealloc];
}

An exception is thrown. It says that self has not been added as an observer. This only happens in a certain case, after [CATransaction fl开发者_如何学编程ush] is called.

I used Instruments to see when the object was allocated. It says it was allocated with the call CALayerGetPresentationLayer(). I am not sure how this works, but I guess this is a copy of my original layer, so init was never called, and I was never added as an observer.

How can I either check that I am an observer before removing myself, or maybe tell if I am a presentation layer?

Bridger Maxwell

I found a good solution here: https://stackoverflow.com/a/6714561/958017

you can use a try-catch block in your call to removeobserver:

@try{
   [[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"showColorLabels"];
}@catch(id anException){
   //Whatever you want to do.
}

Welllll.... to ask the obvious question in response:

Where are you adding self as an observer of the @"showColorLabels key?

You shouldn't have to invoke -removeObserver:forKeyPath: unless you explicitly added the object as an observer in the first place.