title: Enlarge MKCoordinateRegionForMapRect For some margin
body: <p>I have some annotations presented on a map (somepoints)
  the map zooms in or out to fit all points - see working code below.</p>
  
  <pre><code>MKPolygon *poly = [MKPolygon polygonWithPoints:somepoints count:i];
  [self.mapView setRegion:MKCoordinateRegionForMapRect([poly boundingMapRect]) animated:NO];
  </code></pre>
  
  <p><strong>Q</strong>: I would like to expand this poly just slightly to have some margins, how can I enlarge this Region?</p>