iOS 在viewDidLayoutSubviews自动布局crash问题

1 viewDidLayoutSubviews改成viewWillLayoutSubviews在iOS7上就不会crash了
2 viewDidLoad中还需要设置self.edgesForExtendedLayout = UIRectEdgeNone;iOS7强调全屏布局，navigationBar会遮挡部分布局，关掉他。

顺便记一下生命周期函数调用顺序：

viewWillAppear:animated:

viewWillLayoutSubviews

viewDidLayoutSubviews

viewDidAppear:animated:

2021-12-11
2022-12-23
2021-05-26
2021-06-22
2021-10-01
2022-12-23
2022-12-23
2022-12-23