title: Displaying custom UIView in callout of pin(annotation) in map, using MapKit
body: <p>In my application i want to display custom view(with buttons) in the case of user touches annotation on map(standard pin).
  i know that i can subclass MKAnnotationView and change the view of pin. but how can i change the look of Additional information view, that appears when user touches pin(by default it displays title and subtitle of MKAnnotation object).
  how can i do this?</p>
  
  <p>Thanks.</p>