title: Track selection of user location annotation in MKMapView
body: <p>I have an iPhone app that zooms to the nearest city of the user's location and I want the user to be able to double tap on the <strong>userLocation annotation</strong> and have the map zoom into about a block or so. </p>
  
  <p>How do I get the <code>userLocation</code> annotation to recognize that it's being tapped?</p>