layoutSubview 调用时机

• init does not cause layoutSubviews to be called (duh)
• addSubview causes layoutSubviews to be called on the view being added, the view it’s being added to (target view), and all the subviews of the target view
• setFrame intelligently calls layoutSubviews on the view having it’s frame set only if the size parameter of the frame is different
• scrolling a UIScrollView causes layoutSubviews to be called on the scrollView, and it’s superview
• rotating a device only calls layoutSubview on the parent view (the responding viewControllers primary view)
• removeFromSuperview – layoutSubviews is called on superview only (not show in table)