ios-视图控制器跳转时生命周期的调用
A -> B (Push)
A -->viewWillDisappear
B-->viewWillAppear
A-->viewDidDisappear
B-->viewDidAppear
A -> B(Present)
A -->viewWillDisappear
B-->viewWillAppear
B-->viewDidAppear
A-->viewDidDisappear
A -> B (Push)
A -->viewWillDisappear
B-->viewWillAppear
A-->viewDidDisappear
B-->viewDidAppear
A -> B(Present)
A -->viewWillDisappear
B-->viewWillAppear
B-->viewDidAppear
A-->viewDidDisappear