CALayer：在图层内容上维护cornerRadius

Question

I've been looking at the CALayer's documentation and it seems like cornerRadius only affects the background of the layer and not the contents .

Is there a way to apply the corner radius to the entire CALayer without taking a big performance hit?

I've seen suggestions about masks, but that sounds costly. I've also seen suggestions about drawing the contents manually, but I don't really know where to start. I know a bit about rendering images in contexts, but I don't know how I'm supposed to draw it onto the CALayer 's content view with a corner radius. The best I would know is to subclass CALayer and override the drawInContext method and use CGContextDrawImage .

All help is greatly appreciated, but to reiterate the question : "Is there a way to apply the corner radius to the entire CALayer without taking a big performance hit?"

Answer 1

cornerRadius does apply to the entire CALayer and it does not cause a big performance hit. If you are not seeing the contents with rounded corners, it is because you have forgotten to set masksToBounds to YES.