You should override this method only if the autoresizing and constraint-based behaviors of the subviews do not offer the behavior you want. 意思是當你需要調整subview的大小的時候,重寫layoutSubviews方法。 layoutSubviews在以下情況下會被調用: init初始化不會觸發(fā)layoutSubviews addSubview會觸發(fā)layout...