How to dump CALayer into CGImageRef?

I have some custom, CoreAnimation based UI. I'd like to implement mouse dragging开发者_StackOverflow中文版 of certain CALayers and I'd like to stick an image of dragged layer to the cursor. The problem is, that I can't get the CALayer (which isn't image/.contents based) into an image of some kind - like CGImageRef or NSImage. Any ideas?

CALayer has a renderInContext: method, which accepts a CGContextRef.
After rendering to the context, you can obtain a CGImageRef by calling CGBitmapContextCreateImage(CGContextRef context).

I already answered a similar question here.