title: Adding and removing annotations from MapView leads to a blink
body: <p>in my app I'm adding and removing annotations to my map view, but actually even if I first add the new ones and then remove the old ones there is a blink of the annotations</p>
  
  <p>The new annotations are received from the internet and so I can't just remove them from the array of the new ones...</p>
  
  <p>My question is how does it come to the blink behavior and how I can avoid this?</p>
  
  <p>I don't want to iterate through the annotations and compare each's location...
  So I tried to delay the remove and ended up at 0.2 seconds. With exactly this delay there is no visible blink, but this isn't desirable at all.</p>
  
  <p>Thanks</p>
  
  <pre><code>    NSMutableArray *annotationsToRemove = [[NSMutableArray alloc] initWithArray:[_mapView annotations]]; 
      [annotationsToRemove removeObject:[_mapView userLocation]];
      [_mapView addAnnotations:locations];
      // [_mapView performSelector:@selector(removeAnnotations:) withObject:annotationsToRemove afterDelay:0.2];
      [_mapView removeAnnotations:annotationsToRemove];
  </code></pre>
  
  <p>("locations" is my array of new annotations)</p>