title: How to add a user tracking button to MKMapView?
body: <p>I would like to add a button on a MKMapView to move the map to the current user location. I saw this icon on plenty of applications :</p>
  
  <p><img src="https://i.stack.imgur.com/pN12J.png" alt="Google Maps&#39; Button"></p>
  
  <p>Is there any class for this ? Or should I create it myself ? I know I can use <code>MKUserTrackingBarButtonItem</code> but I don't wan't to use a Navigation Bar.</p>