title: How to render MKMapView outside main thread?
body: <p>Good day everybody!</p>
  
  <p>I'm developing application for iPhone. I have table view and list of locations that I need to display to user. For this purpose I used MKMapView in every table view cell. But when there are a lot of locations this solution becomes very slow. I want to improve UI performance and replace MKMapView with UIImageView. So I need to render map from MKMapView to UIImage in some NON-MAIN thread. I tried to do it like this:</p>
  
  <pre><code>UIGraphicsBeginImageContext(CGSizeMake(64, 64));
  CGContextRef context = UIGraphicsGetCurrentContext();
  [[mapView layer] renderInContext:context];
  thumbnail_image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  </code></pre>
  
  <p>But this code renders only yellow background of the map and pin above specified location. There is no map data such streets, houses, etc. What did I do wrong? Thank You for advice.</p>