presentingViewController? 正在跳轉(zhuǎn)的controller
presentedViewController 跳轉(zhuǎn)完的controller
parentViewController 父controller
presentationController 跳轉(zhuǎn)狀態(tài)的controller
popoverPresentationController 采用導(dǎo)航欄跳轉(zhuǎn)狀態(tài)的control
view.presentingviewcontroller.presentingviewcontroller?
A. presentedViewController = B
B. presentingViewController = A