So it’s great that the split view gives us one behavior for the iPad and another for the iPhone.
Except, well, that the iPhone 6-series devices are really big. Maybe not iPad big, but it at least makes you wonder whether it’s really appropriate to lump all iPhones together. After all, iOS 9 runs on everything from the 4s (with its 320×480, 3.5-inch screen) to the iPhone 6s Plus (414×736, 5.5-inch screen). Even within the iPhone range, there may be times we want to go to a side-by-side mode with our split view.
To do so, we need to understand how iOS represents screen sizes and their contents.
In iOS, screens, view controllers, and views all have a collection of sizing information called a trait collection ...