Push (A -> B)
B : viewDidLoad
A : viewWillDisappear
B : viewWillAppear
A : viewDidDisappear
B : viewDidAppear
Pop (A <- B)
B : viewWillDisappear
A : viewWillAppear
B : viewDidDisappear
A : viewDidAppear
B : dealloc
Push (A -> B)
B : viewDidLoad
A : viewWillDisappear
B : viewWillAppear
A : viewDidDisappear
B : viewDidAppear
Pop (A <- B)
B : viewWillDisappear
A : viewWillAppear
B : viewDidDisappear
A : viewDidAppear
B : dealloc