title: Smooth annotation movement on OS 4
body: <p>To move custom annotations in my MKMapView class, I remove all annotations first and add them (which are placed in new locations) again every second. It was perfectly working on iOS 3 but when I updated my OS and XCode to version 4.0, the annotations blink instead of having the smooth movement they used to have in previous version.</p>
  
  <p>How can I keep this smooth movement?</p>