title: Differentiate between land and water on map view iphone sdk
body: <p>I am implementing a map in which I need to customise the colour of the map. i.e in world map I need to show the surface area covered by land with gray colour and the surface area covered by water with black.I am using overlay for this. But I am not getting how to get the co-ordinates of land and water. Can anybody please help me with this. </p>