[UINavigationController retain]: message sent to deallocated instance

Question

My application crashes when simulating Memory warning in simulator with error:

[UINavigationController retain]: message sent to deallocated instance<

Answer 1

It is likely you are using an assign or __unsafe_unretained property somewhere in your code. Delegates should always be of type weak, so that the reference to the delegate object is nil'ed out on deallocation.

Also, calling:

[((WPRAppDelegate*) [UIApplication sharedApplication].delegate) startWithFlash];

... from within another class in your app is a bit of a smell. One that I've had many times. It means you have circular dependencies. Your app delegate is dependent on the class using this code (transitively, if not directly), and this class is dependent on your app delegate. Looking at your Instruments trace, it looks like you have adopted the delegate pattern else where, so you have some experience with decoupling. I would suggest bubbling that message up through a delegate chain, notification, or block.