Animate change of view controllers without using navigation controller stack, subviews or modal controllers?
NavigationControllers have ViewController stacks to manage, and limited animation transitions. Adding a view controller as a sub-view to an existing view controller requires passing events to the sub-view controller, which is a pain to manage, loaded with little annoyances and in general feels like a bad hack when implementing (Apple also recommends against doing this). Presenting a modal view controller again places a view controller on top of another, and while it doesn't have the event passing problems described above, it doesn't really 'swap' the view controller, it stacks it. Storyboards