Swift version: 5.0
All views have an intrinsic content size, which refers to the amount of space the view needs for its content to appear in an ideal state. For example, the intrinsic content size of a
UILabel will be the size of the text it contains using whatever font you have configured it to use.
Intrinsic content sizes are important because they allow views to have a natural width and height without us forcing one. For Auto Layout to work it must know where each view is positioned precisely: its X, Y, width, and height values. With intrinsic content size we can say “place this button 20 points from the top and center it horizontally” and that’s enough to form a complete layout – Auto Layout can calculate the rest based on the button’s intrinsic size.
Although Auto Layout does its best to give views the space they need based on their intrinsic content sizes, all views also have a content compression resistance priority and a content hugging priority that determine how much it fights to retain its intrinsic content size when available space is less than or greater than it needs, respectively.
Available from iOS 6.0
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.