How to come back to Tabbar controller after presenting few modal view controllers

问题

Here is my view hierarchy

Login ————> Dashboard(Tabbar controller with 3 VC's). From one V.C of tabbar controller Presented 4 VC's one after the other modally.

————> V.C.1————>V.C.2————>V.C.3————>V.C.4.

1.How to go back to tabbar controller from VC4?

2.My app crashes some times due to memory. As i don’t have any back button in all view controllers, i want to remove V.C.1 from memory while presenting V.C.2 and V.C.2 while presenting VC3 etc .. what is the best way to achieve this ?

3.I have a logout button in one of my view controllers in tabbar,What is the best way to present log in screen? (Currently i was conected segue to login.Is this the correct way?)

Thank you..

来源：https://stackoverflow.com/questions/40844571/how-to-come-back-to-tabbar-controller-after-presenting-few-modal-view-controller