title: Remove MKMapView Annotations with a certain pinColor?
body: <p>Is it possible to remove all annotations on a given MKMapView of a given pinColor? I'm trying to clear all user-entered annotations (pins) on my map before displaying new ones for a part of my app, but I didn't know how granular I can be in selectively removing annotations...</p>
  
  <p>I'd like to just remove all annotations that have MKPinAnnotationColorGreen (green) pins, but I'd also be able to simply remove all pins entered by the user, if there's a way I could track those.</p>
  
  <p>I know I could simply do:</p>
  
  <pre><code>[myMapView removeAnnotations:myMapView.annotations];
  </code></pre>
  
  <p>... then redraw all the annotations I want, but that seems like a waste of resources.</p>
  
  <p>Any advice?</p>