UIStackView Tutorial: A Comprehensive Guide to iOS Linear Layout

This article provides a comprehensive guide to UIStackView , Apple's linear layout container introduced in iOS 9 within the UIKit framework. The tutorial begins by explaining the technical background, drawing parallels to web Flex layout concepts such as flex-direction , flex-wrap , justify-content , align-items , and align-content .

UIStackView adopts Flex's layout philosophy, providing a linear arrangement approach for organizing subviews with minimal code. It serves as a container that manages the layout of its arranged subviews without directly participating in screen rendering—note that overriding drawRect: has no effect.

The core parameters covered include: Axis ( horizontal / vertical ), Distribution ( fill , fillEqually , fillProportionally , equalSpacing , equalCentering ), Alignment ( fill , top , center , bottom , firstBaseline , lastBaseline , trailing , leading ), and spacing for controlling the minimum distance between subviews.

Basic usage involves adding subviews via addArrangedSubview: rather than addSubview: . The article demonstrates a practical example with two UILabels and a separator line centered together.

Advanced features include hiding subviews dynamically (which removes them from the layout calculation) and managing content hugging/compression resistance priorities using setContentHuggingPriority:forAxis: and setContentCompressionResistancePriority:forAxis: to control how subviews stretch or compress.

The article concludes by noting UIStackView 's limitations compared to Flex layout—specifically the inability to individually control properties like order , flex-grow , and flex-basis on subviews.