title: iOS 7 annotation pin image changed when pin is dragged
body: <p>I have an annotation pin that I use to display the current search location which can be dragged. This annotation is just a normal MKPointAnnotation which I then change the image in the viewForAnnotation method. This is fine until I begin to drag the annotation, after which the annotation changes to the default red pin and loses the custom image I had set.</p>
  
  <p>I create and add the annotation like this:</p>
  
  <pre><code>MKPointAnnotation *userAnnotation = [[MKPointAnnotation alloc] init];
  [userAnnotation setCoordinate:userCoordinate];
  [userAnnotation setTitle:@"My Location"];
  [userAnnotation setSubtitle:@"Drag to move - Press to reset"];
  
  [self.mapView addAnnotation:userAnnotation];
  </code></pre>
  
  <p>Then I set the annotationView like this:</p>
  
  <pre><code>- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id &lt;MKAnnotation&gt;)annotation {
  ....
  [annotationView setImage:[UIImage imageNamed:@"locationpin"]];
  [annotationView setDraggable:YES];
  [annotationView.layer setZPosition:999];
  return annotationView;
  </code></pre>
  
  <p>And I implement the method didChangeDragState: fromState: like so:</p>
  
  <pre><code>- (void)mapView:(MKMapView *)mapView
   annotationView:(MKAnnotationView *)annotationView
  didChangeDragState:(MKAnnotationViewDragState)newState
     fromOldState:(MKAnnotationViewDragState)oldState {
  
      if (newState == MKAnnotationViewDragStateEnding) {
          CLLocationCoordinate2D droppedAt = annotationView.annotation.coordinate;
          self.mockLocation = [[CLLocation alloc] initWithLatitude:droppedAt.latitude longitude:droppedAt.longitude];
  
          NSLog(@"%@ mock location set to %f %f", [self class], droppedAt.latitude, droppedAt.longitude);
  
          [self plotStations];
      }
  }
  </code></pre>
  
  <p>I don't recall this issue on iOS 6 but it is for sure existing on iOS 7.</p>
  
  <p>So, how can I make it retain its image before, during, and after dragging?</p>