title: iOS MapBox - get annotation title in imageForAnnotation method
body: <p>In the following method:</p>
  
  <pre><code>- (MGLAnnotationImage *)mapView:(MGLMapView *)mapView imageForAnnotation:(id &lt;MGLAnnotation&gt;)annotation{
  </code></pre>
  
  <p>used to display a custom annotation UIImage, I would like to be able to differentiate my annotations (I can have 3 different types).</p>
  
  <p>Ideally, I would like to be able to have a <code>tag</code> on the MGLAnnotation to easily identify what type of annotation it is, but I can also use a combination of the title, latitude and longitude to do so.</p>
  
  <p>But in the method, I am unable to get the <code>annotation.coordinate</code>, or <code>annotation.title</code>.</p>
  
  <p>How come? Can I make this properties accessible?</p>