A constraint-based layout system that allows developers to create an adaptive UI that responds appropriately to changes in screen size and device orientation. Auto Layout dynamically calculates the size and position of all the views in your view hierarchy. What’s more, it is compatible with many of Apple’s most exciting APIs, including animations, motion effects, and sprites.
|Apple, Google, Microsoft
In the beginning, Apple made only one screen size for the iPhone. And it was good. Developers had an easy time creating interfaces that didn’t have to be terribly flexible, as they really only had to fit that one size. Fast forward to today, and you’re in a much different world: different sized iPhones, iPads, and more emphasis on landscape mode all demand user interfaces of different sizes. Rather than expect developers to create different interfaces for each screen size, Apple came up with a system for allowing elements within a user interface to grow, shrink, and move depending on the size of the screen... and they called it Auto Layout.