title: Remove GMSPolyline from GMSMapView
body: <p>I am using GoogleMap-IOS-1.8.1 SDK for displaying a map. I have to draw a GMSPolyline on the map. After a particular event I have to remove all GMSPolyline paths except for markers.  I'm not sure of the best way to do that.
  The GoogleMaps documentation for iOS describe two methods to sue.</p>
  
  <pre><code> 1. [mapView_ clear];
   2. Set the GMSPolyline map property to nil
  </code></pre>
  
  <p>Here the first approach removes all Markers and Overlays as well. This isn't exactly what I want.
     And for 2nd one it doesn't seem like the best method to save all of the GMSPolyline object references and then go back and set them all to nil.</p>
  
  <p>Is there a better way to do accomplish this task, or is this the only proper / correct way to do this?</p>
  
  <p>I was hoping for something like the following.</p>
  
  <pre><code>for (GMSPolyline *polylineToremove  in mapView_.polyline)
  {
      [mapView_ removeOverlay:overlayToRemove];
  }
  </code></pre>