Question

I have a problem in my application.

Answer 1

You need to set the delegate property of your map view to nil in -viewDidUnload:. This crash is occurring because the map view attempted to message it’s delegate, your view controller, but it had already been deallocated once it was popped off the stack.

Apple even mentions this in passing in the 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.

They recommend nilling the delegate in -dealloc, but because of ARC, -viewDidUnload is the best bet moving forward.

- (void)viewDidUnload
{
    self.mapView.delegate = nil;
    self.locationManager.delegate = nil;
    [super viewDidUnload];
}