ios7 - can not override GetRendererForOverlay on monotouch -

i want draw overlay on top of mkmapview defined delegate class defining view of overlays. can see seems ios 7 recommended use getrendererforoverlay instead of getviewforoverlay. problem can not find method name getrendererforoverlay override. in better word seems mkmapviewdelegate has not virtual method overriding getrendererforoverlay. how should use it?

public class mymapdelegat : mkmapviewdelegate {       [obsolete ("since ios 7 recommnended use getrendererforoverlay")]     public override mkoverlayview getviewforoverlay (mkmapview mapview, nsobject overlay)     {         // note: don't call base implementation on model class         // see http://docs.xamarin.com/guides/ios/application_fundamentals/delegates,_protocols,_and_events         throw new notimplementedexception ();     }  } 

i read document has been suggested on note not find thing getrendererforoverlay.

you can method getviewforoverlay ios7. need call

var circleoverlay = mkcircle.circle (mapview.centercoordinate, 1000); mapview.addoverlay (circleoverlay); 

somewhere else fire above method.