There are two types of segues (transitions) between view controllers: push and modal.
A push segue adds the new controller to the top of the nav stack and gives it the screen. It can then push new view controllers itself, or pop itself from the stack.
A modal segue presents one view controller that can do nothing but remove itself from the screen. Modal segues are useful for presenting controllers that will not need to present other controllers, such as confirmation screens, social presentation screens, etc.
Implement by selecting “Modal” when right-click dragging in IB, or using
self.presentViewController(controller, animated: true, completion: nil)