IOS: layoutSubviews

IOS: layoutSubviews

LayoutSubviews is the attribute method in UIView, that is, this method can be used as long as it inherits from UIView. This method is also very powerful. The following is his triggering time:

1. Initialization of init will not trigger layoutSubviews
2. addSubview triggers layoutSubviews
3. Setting the view Frame triggers layoutSubviews. Of course, the premise is that the frame value is changed before and after the Frame value is set.
4. Rolling a UIScrollView triggers layoutSubviews.
5. Rotating Screen triggers the layoutSubviews event on the parent UIView.
6. Changing the size of a UIView triggers the layoutSubviews event on the parent UIView.

In these scenarios, we can use it, such as changing data. This is a good method.
You can also manually call

[Self setNeedsLayout];

Note: To Call layoutSubviews, you also need to call its parent class method, that is

[Super layoutSubviews]

It is said that a strange problem may occur if you do not call it.