title: How to trigger MKAnnotationView's callout view without touching the pin?
body: <p>I'm working on a <code>MKMapView</code> with the usual colored pin as the location points. I would like to be able to have the callout displayed without touching the pin.</p>
  
  <p>How should I do that? Calling <code>setSelected:YES</code> on the annotationview did nothing. I'm thinking of simulate a touch on the pin but I'm not sure how to go about it.</p>