问题:

I have an MKOverlayView that displays animated radar data as a series of images. The issue I have is that the radar images are chopped into tiles by MapKit. To swap images I have a timer that calls an update function which sets the current image in my overlay and then calls the following

[myRadarOverlayView setNeedsDisplayInMapRect:self.mapView.visibleMapRect];

The overlay updates, but does so one tile at a time so I get a choppy animation. Any ideas about how make all the tiles animate (i.e. swap images) at the exact same time?

回答1:

I solved this by adding a UIImageView as a subview of the MKOverlayView.

To animate, stop drawing with the normal drawMapRect:zoomScale:inContext: (via an instance variable/property flag) and draw to the UIImageView instead (to the animationImages property), then use startAnimating.
You can handle panning and zooming by reinitializing the UIImageView in response to mapView:regionDidChangeAnimated:.

回答2:

Sample code how to animate a circle:

http://yickhong-ios.blogspot.com/2012/04/animated-circle-on-mkmapview.html

回答3:

Is there a callback when all the tiles have finished loading? If so, you could go with double buffering, and update the view offscreen, and then switch it in.