NullPointerException in ItemizedOverlay.getIndexToDraw

I have a relatively simple MapActivity that I'm trying to make display a list of "camps" within a given map region. I've created a custom subclass of OverlayItem called CampOverlayItem, a custom ItemizedOverlay called CampsOverlay that returns CampOverlayItems, and of course a MapActivity subclass that populates the map.

MapView and dealloc IOS

Hello i have a mapView and i think it takes too much memory after leaving the mapView