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Editorial Team
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Asked: 2026-05-24T18:05:09+00:00

I’m wondering whether I need to check if something is within the bounds of

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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:containingRect]. 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?

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1 Answer

  1. Editorial Team

    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!

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