iOS Components and Frameworks: Understanding the Advanced Features of the iOS SDK

Understanding the Coordinate Systems

There are two coordinate systems at work in MapKit: the coordinate system for the map, and the coordinate system for the view. The map uses a Mercator Projection, which takes the 3D map of the world and flattens it into a 2D coordinate system. Coordinates can be specified using latitude and longitude. The map view represents the portion of the map displayed on the screen using standard UIKit view coordinates. The map view then determines where in the view to display points determined by map coordinates.