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 pace, heavy use of storyboards would make it a rather tough to port the app to the other platform since these design features are specific to the iOS platform. This is when pure code would be more beneficial. Storyboards though give us developers an editable, visual representation of the app/game we wish to make and the ability to do little to no changes as the family of devices change.

Even other game development engines, such as Unity, Unreal Engine, and more, work on a more sandboxing, visual representation methodology with your code acting as more of a component to the visual as opposed to the full structure of everything that appears before your game characters even get rendered to the screen.