Drawing Inner Shadow with CoreGraphics

I know that you can use CGContextSetShadow to draw a drop shadow, but is there any w开发者_开发知识库ay to draw an inner shadow?

This implies that what you're drawing has an interior to view the shadow through. I further presume that you don't want the shadow to appear outside what you're drawing.

So, clip to the outline of what you're drawing, and then draw with shadow as normal.