Question

It’s not clear, to me anyway, if a UIView is automatically released from its superview if you use addSubview to add it to another view?!? I know a view can only have ONE superview but I’m not clear about how, exactly, to go about moving a subview from one superview to another.

retain view, release (from old superview), addSubview to new superview

or

simply addSubview to new superview?

Answer 1

To the question of whether the view is released when -removeFromSuperView is called, it is, and this is documented in the UIView reference under -removeFromSuperView. It is not as explicitly stated that -addSubView: calls -removeFromSuperView, but it is implied and can be tested by overloading -removeFromSuperView in a UIView subclass.

Therefore I can think of no reason to call -removeFromSuperView in this case. There’s no memory-management reason to do it, so this is adding some code complexity (and therefore potential errors) for little value. Even in cases where I wanted to emphasize to later developers that this view is changing view hierarchy, I would use a comment rather than the extra retain/release here.