Storyboard and XIB files can be used in conjunction with size classes. You can think of this as the ability to specify different layouts in the same file without adding a single line of code.
This is obviously a huge improvement to our workflow; among other things, we can now define universal applications using the same Storyboard for iPad and iPhone without duplicating all the IBOutlet and IBAction connections and subsequently update just a single file instead of keeping two different Storyboards synchronized.
Let's explore this with a simple example of how easy it is to handle size classes with Interface Builder.
The main goal of the next example is creating a layout that's suitable for iPhone and another one that looks great on iPad, using the same Storyboard for both. We will create a simple hierarchy based on two views that we will call "Menu view" and "Detail view". It is something similar to what we can obtain using UISplitViewController...