I\'m using a MKMapView
inside an iPhone app. When I click a button the zoom level must increase. This is my first approach:
MKCoordinateRegion z
I use similar code to yours and it seems to work. What may be happening is that your delta is not changing enough to cause the zoom level to increase from one google zoom level to the next. This would also depend on the initial state of your map, which could explain why it is intermittent - so how do you set the map and zoom level up to begin with, before the user presses the zoom button?
You could also look into the regionThatFits method which will adjust the region you provide (name is from memory as I don't have the apple docs handy).