setNeedsDisplayInMapRect doesn't trigger new drawMapRect: call

Question

I\'m using a custom MKOverlay/MKOverlayView to completely cover the Google basemap with my own tiles, which are loaded asynchronously. I follow the pattern of

Answer 1

The answer above did not work for me. From the NSLog printout I used I could see that a different thread was being used for despite grabbing the dispatch_get_current_queue() in canDrawMapRect and storing it for later use. This was the case in the iPad 4.3 Simulator at least, I did not attempt on the device.

My solution was less satisfactory and more error prone solution of wait x time before calling.

-(void)setNeedsDisplay:(WebRequest*)webRequest
{  
   [webRequest retain];
   dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.25 * NSEC_PER_SEC), dispatch_get_main_queue(), 
   ^{
      [webRequest autorelease];
      [delegate setNeedsDisplayInMapRect:webRequest.request.requestedMapRect 
                              zoomScale:webRequest.request.requestedScale];
   });     
}