title: How to show single annotation pin for a region when i have multiple coordinates for that region?
body: <p>I am working on the map application and as per requirement i need to show a single pin for a single region even if it has multiple user coordinates when its completely zoomed out but when its zoomed in to the map then i should display all the pins as per its coordinates. 
  I have given example below to explain my problem. 
  I have city New York on this city I have 100 pins on my mapview when I am zooming out of my map it should show me only one annotation pin on the place of 100 pins but when I am zooming in then it should show again 100 pin on map.
  Does any one knows about this. I need suggestion. Please note that I am getting all the  locations from web services except my current location. This should not be affecting application so that application shouldn't become slow.</p>
  
  <p>Please suggest some solution.</p>