title: In which case that mapView:viewForAnnotation: will be called?
body: <p>Now I want to add a static pin annotation on map in my iOS app.</p>
  
  <p>But I just want to know if the delegate method mapView:viewForAnnotation: will be called.</p>
  
  <p>In the Apple documentation, it is said that</p>
  
  <pre><code> When it needs an annotation view, the map view calls the mapView:viewForAnnotation:    method of its delegate object. 
  </code></pre>
  
  <p>I have read several tutorials from Internet and official documentation from Apple.
  And I still don't when this method will be called.</p>