UIView: how to do non-destructive drawing?

Question

My original question:

I\'m creating a simple drawing application and need to be able to draw over existing, previously drawn content in my d

Answer 1

This seems like a better method than I've been using. That is, in a touches event I make a copy of the view about to be updated. Then in drawRect I take that image and draw it to the view and make my other view changes at the same time.

But this seems inefficient but the only way I figured out how to do it.