This view never gets old.
Now that Xcode 4 is no longer under NDA, I am going to be posting some tips here.
If you have an application that uses a UITabBarController as it’s main navigation, you no doubt have set up the tabs to have different types of controllers.
If you wanted to change the type of controller for a particular tab, in the Interface Builder of Xcode 3 there was a UI to allow you to change the type (this shows the change in the settings tab to a navigation controller):
In Xcode 4 however no such UI exists. Your best bet is to delete that particular tab and re-add it as the particular controller you want. In my case I was switching from a general view controller to a navigation controller: