两个 UIViewController 之间页面切换的生命周期

两个 UIViewController 之间页面切换的生命周期

如下所示：

A push to B:

 [A.navigationController pushViewController:B animated:animated];

1. A viewWillDisappear:
2. B viewWillAppear:
3. A viewDidDisappear:
4. B viewDidAppear:

B pop back to A:

[B.navigationController popViewControllerAnimated:animated];

1. B viewWillDisappear:
2. A viewWillAppear:
3. B viewDidDisappear:
4. A viewDidAppear: