ViewController加载完成以后，旋转屏幕，会触发以下事件：

　　注：ShowViewCycle是ViewController的SubView

1. -[ViewController willTransitionToTraitCollection:withTransitionCoordinator:] [Line 76] newCollection:<UITraitCollection: 0x7f8f22d6a5a0; _UITraitNameUserInterfaceIdiom = Phone, _UITraitNameDisplayScale = 2.000000, _UITraitNameHorizontalSizeClass = Compact, _UITraitNameVerticalSizeClass = Compact, _UITraitNameTouchLevel = 0, _UITraitNameInteractionModel = 1> coordinator:<_UIViewControllerTransitionCoordinator: 0x7f8f22d67660>

2. -[ViewController viewWillTransitionToSize:withTransitionCoordinator:] [Line 63] coordinator:<_UIViewControllerTransitionCoordinator: 0x7f8f22d67660>, size width:667.000000 hight:375.000000

　　2.1 -[ShowViewCycle translatesAutoresizingMaskIntoConstraints] [Line 393] 

　　2.2 -[ShowViewCycle translatesAutoresizingMaskIntoConstraints] [Line 393] 

　　2.3 -[ShowViewCycle translatesAutoresizingMaskIntoConstraints] [Line 393] 

3. -[ViewController viewWillLayoutSubviews] [Line 186] 

4. -[ViewController updateViewConstraints] [Line 387] 

　　4.1 -[ShowViewCycle translatesAutoresizingMaskIntoConstraints] [Line 393] 

　　4.2 -[ShowViewCycle alignmentRectInsets] [Line 434] 

5. -[ViewController viewDidLayoutSubviews] [Line 196] 

　　5.1 -[ShowViewCycle layoutSubviews] [Line 231]