layoutSubviews的触发时机

• init does not cause layoutSubviews to be called (duh)

init方法不会触发

• 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

addSubview在目标视图被添加子视图的时候触发

• view setFrame intelligently calls layoutSubviews on the view having its frame set only if the size parameter of the frame is different

view的frame发生变化的时候触发

• scrolling a UIScrollView causes layoutSubviews to be called on the scrollView, and its superview

scrollview和它的父视图滚动的时候触发

• rotating a device only calls layoutSubview on the parent view (the responding viewControllers primary view)

转旋设备的时候，相应的视图控制器对应的主视图会触发

• Resizing a view will call layoutSubviews on its superview

改变视图大小的时候会在视图的父视图上触发

stackoverflow链接