How to clear and then redraw a quartz drawing

Question

I'm making a complex drawing using quartz based on passed in information. The only part I haven't been able to figure out is how do I clear the lines, rectangles, etc that I've already drawn? Basically, I want to erase the whole drawing and just draw it again from the new data.

Answer 1

If you set your UIView's clearContextBeforeDrawing property to YES, then the system should take care of filling its area with its backgroundColor before calling its drawRect: method.

Answer 2

If you want to clear something that's not tracked as part of the current state, it's probably less expensive to just release your old context and start a new one.