Does drawRect: automatically check whether something is within the bounds of the CGRect passed to it?

I'm wondering whether I need to check if something is within the bounds of the CGRect passed to drawRect:, or if drawRect: automatically handles that for me.

For example, assume that I have 10 UIBezierPaths on the screen. Each curve is in an NSMutableArray named curves. Every time drawRect: is called, it loops through this array and draws the curves it finds there. If the use moves one curve, I find its containing CGRect and call [self setNeedsDisplayInRect:con开发者_Go百科tainingRect]. In my drawRect: implementation, do I need to personally check whether each of the UIBezierPaths falls within the CGRect passed to drawRect: (using CGRectIntersectsRect), or is that handled automatically?

This falls into a class of optimizations you'll have to make yourself if you think it's necessary after profiling.

UIKit isn't that smart unfortunately. Though it would probably be too slow if it was!