Using drawRect, setNeedsDisplay and layoutSubViews

Is there any ground rule for using methods like drawRect, setNeedsDisplay and layou开发者_高级运维tSubViews? I believe they adversely affect the app performance. Is there any preferred alternatives for these messages?

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While this isn't an exact duplicate of this question, I believe my answer there still applies.

In summary, -drawRect: will redraw the content within a view, which is an expensive operation. Avoid redrawing if you can by layering content and moving or hiding those layers as needed.

However, these redraws typically will only have a significant performance impact if there are many of them done in rapid succession, like when trying to animate content. One-off redraws of static UI elements will not perceptively slow things down.