Learning iOS Development: A Hands-on Guide to the Fundamentals of iOS Programming

Auto Layout Basics

When there is just one screen size in one orientation, designing a scene means determining what view elements are needed, then placing those elements in the view, or perhaps, in a hierarchy of views. Adding rotation increases the complexity, though it is still manageable. But as soon as you add different screen sizes in addition to interface orientations, things get more complex. Earlier versions of iOS gave you some flexibility in specifying how views adjusted when their container changed size, but usually layouts with view dependencies or mildly complex hierarchies took code. Often that code required complex calculations and updating of many views.

For example, consider running an app on different-height portrait displays. ...