How do I prevent a CALayer from redrawing as its bound change?

Question

i have a CALayer with a custom draw method I've added to my view's base layer. I set needsDisplayOnBoundsChange to NO. However, when I resize the parent view's frame, the layer's drawInContext: is getting called continuously. I'd like the contents to scale while the resize is occurring. Any clues?

Jon Steinmetz Jon Steinmetz · Accepted Answer · 2010-11-08T03:30:27

Interesting, I have a case where I have a CALayer that correctly scales its contents until I call setNeedsDisplay on it to redraw its contents. One thing that may be different is that in my case the layer is being drawn by its delegate and not by a subclass of CALayer. Another thing that may be different is that this is on iOS and not OSX (I don't know which you are using in this case). It is possible that there could be behavior differences between subclasses and delegate drawn layers and/or iOS and OSX.

Another thing to note is that needsDisplayOnBoundsChange is documented to be NO by default, so one should not need to set it. I am not specifically setting needsDisplayOnBoundsChange on my layer.

You could try using a delegate to do the drawing to see if that makes a difference. Note that a UIView cannot be a delegate to a CALayer. In my case I made a simple delegate object that forwards the draw call to my view.

How do I prevent a CALayer from redrawing as its bound change?

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