title: Is there a way to get notified when my UIImageView.image property changes?
body: <p>Is there a way to set an observer on a UIImageView.image property, so I can get notified of when the property has been changed? Perhaps with NSNotification? How would I go about doing this?</p>
  
  <p>I have a large number of UIImageViews, so I'll need to know which one the change occurred on as well.</p>
  
  <p>How do I do this? Thanks.</p>