There's no single correct way to do the design structure of your app as long as the MVC model is followed. Actually, there are programmers out there who are completely fine with just using the initial view controller and never use a single Nib or storyboard file; thus purely building their game controlled by the logic of their code and calls to the various View objects programmatically. In iOS development, there's somewhat of a design split between three main branches, hardcoding, Nibs, and storyboards. The original methodology was coding; Nibs came in later to first allow direct visual editing in Xcode and then that evolved into Storyboards, further built upon with the addition of Auto Layout.

The reason there's a split between some developers and studios on the visual structure methodology of an iOS app is because one drawback to Nibs and storyboards are their lack of portability. If you wanted to port your game to another platform, such as Android, at descent...