I have a MKMapView. Sometimes after my view controller is dismissed, I'll get a EXC_BAD_ACCESS.
I turned on NSSZombies and it looks like the MKMapView's delegate — my view controller! — is being called, despite both the MKMapView and UIViewController subclass being freed. I've checked, and my memory management is correct.
What's going on?
This is because of the way MKMapView works. There's an operation pending, so MapKit is retaining the MKMapView and it hasn't actually been deallocated yet. That isn't itself a problem. The problem is that it's still sending messages to your delegate.
The workaround is simple: As part of your view controller's cleanup set the map view's delegate to nil, which will prevent MKMapView from sending messages to it.
This is documented in MKMapViewDelegate Protocol Reference:
Before releasing an MKMapView object for which you have set a delegate, remember to set that object’s delegate property to nil. One place you can do this is in the dealloc method where you dispose of the map view.
Edit: Give Oscar an upvote as well, just below, who provided the documentation quote here.
Given ARC, I suggest this means you should set your map view's delegate to nil in your view controller's dealloc.
