I am trying to create a fog of war style map where areas I have visited are uncovered and the rest of the map is "hidden". I am using a MKPolygonOverlay that covers the whole map and create inner polygons around all the locations I have visited. However in areas where these inner polygons overlap, that portion of the overlay is still being drawn. As a new user I can't post pictures but here is a link to the image: http://dl.dropbox.com/u/13815916/Screen%20Shot%202012-06-29%20at%204.40.20%20AM.png