In Interface Builder, can't set a UITabBarCotnroller's "Top Bar" to Navigation Controller

I create a new XIB file, drag a UITabBarController in it, and then try to set the Top Bar to Navigation Bar.

No matter what I do, it goes back to Unspecified.

I think I should be able to set the Top Bar to Navigation Bar so I can lay out my views assuming I've got both a tab bar and a navigation bar, shouldn't开发者_StackOverflow社区 I?

Is this intended behaviour???

I think this is an Apple way to remind you that UITabBarController is not supposed to be pushed in UINavigationController. Related question - Tab bar controller inside a navigation controller, or sharing a navigation root view.