title: iOS 10 MapKit previous layer zoom issue
body: <p>I am working in a map application which renders a polyline over a map. I am having an issue when zooming, it keeps the previous polyline on the tile.</p>
  
  <p>I have tried to force redrawing:</p>
  
  <pre><code>[self.mapView reloadInputViews];
  [self.mapView.layer setNeedsDisplay];
  [self.mapView setNeedsDisplay];
  </code></pre>
  
  <p>Also I tried to slow the zoom speed, but the issue is still in there:</p>
  
  <pre><code>[MKMapView animateWithDuration:2
                           delay:0
          usingSpringWithDamping:0.6
           initialSpringVelocity:10
                         options:UIViewAnimationOptionCurveEaseOut
                      animations:^{
                          [self.mapView setVisibleMapRect:unionRectThatFits
                                              edgePadding:UIEdgeInsetsMake(20, 10, 20, 10)
                                                 animated:YES];
                      }
                      completion: nil];
  </code></pre>
  
  <p>Does anyone know about this?</p>
  
  <p><a href="https://i.stack.imgur.com/sx1D3.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sx1D3.png" alt="enter image description here"></a></p>