This question is really basic. What is the performance difference between removing a UIView from the view hierarchy and hiding a UIView?
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Some years have passed between the initial question and the (rightfully) accepted answer. Let me add another factor: In the meantime, Apple has introduced AutoLayout, which — as some say — might come with quite a performance penalty in certain (deep) subview hierarchies.
If you are using AutoLayout, a view that is hidden will still get layouted, as opposed to the removed view (with its reference saved somewhere). Depending on your scenario, this could then make a performance difference.