dealloc problem with instance variables

Answer 1

I suspect that this is not the whole code involving the addAnnotation variable. Most likely [mapView removeAnnotation:addAnnotation];, which releases addAnnotation, already makes the reference count drop to zero. Do you have something like this in your code somewhere ?

 [mapView addAnnotation:addAnnotation];
 [addAnnotation release];

If so, then you have transfered the complete ownership of addAnnotation to the mapView and you don't need to release it in showAddress any more, which means that removeAnnotation: is enough.