title: How to tell when MKMapView and visible MKAnnotationView are finished drawing?
body: <p>I'm displaying a MKMapView with MKAnnotations some of which are selected and showing their Annotation.
  I am trying to grab an image of the displayed map and annotations using the -renderInContext.</p>
  
  <p>90% of the time the Map, MKPinAnnotationView's and selected annotations are correctly captured.
  The other 10% of the time the image is missing something, usually the MKPinAnnotationViews or their annotations if selected.</p>
  
  <p>I've added code to deal with the Map itself loading it's map data.</p>
  
  <p>But I haven't been able to track down something that would indicate to me that all of the visible MKPinAnnotationView's have been drawn
  and if selected their annotations displayed??</p>
  
  <p>the closest hint I've come across is the addObserver, although I haven't figured out what could be observed that would tell me when all of the drawing is done.</p>
  
  <p>Thoughts?</p>