title: Detecting when a user scrolls MKMapView a certain distance?
body: <p>I want to determine if a user has scrolled more than a certain percentage of the map then disable centering of the map from the user location (similar to how the Maps app works).</p>
  
  <p>I'm not sure which methods to make use of.</p>
  
  <p>I think it would be straightforward to create a rectangle and see if the rectangle contains the current center point, however I have to target IOS 3, so I can't make use of many of the newer Mapkit apis.</p>
  
  <p>I've tried futzing with CLLocation, and using distanceFrom, between the current mapcenter, and the users location, but I'm trying to figure out if that distance is a certain percentage.</p>