Improving Auto Layout structures with UIStackView

Along with iOS 9, comes a long list of new features. The UIStackView class is one of the most interesting for sure.

Getting used to Auto Layout requires a bit of perseverance, but even when you already feel comfortable with the tool, you need to deal with the maintenance of your constraints. Depending on the complexity of the user interfaces, you might find yourself surrounded by constraints! Even if you try to keep the structure well organized, a day will come when you really need to add "those new buttons", and your well-organized structure eventually needs to be reorganized by deleting, moving, and creating new "stuff".

Thanks to UIStackView, we can dramatically simplify this structure by leveraging a system built on Auto Layout that hides most of the UI complexity by handling constraints for us automatically.

A stack view is essentially an element that's capable of displacing its subviews autonomously along a predefined axis: vertical or...