NEW: Nominations are now open for the 2019 Swift Community Awards! >>

How to position a view using Auto Layout anchors

Swift version: 5.1

Paul Hudson    @twostraws   

Auto Layout anchors make it easy to position your views relative to others. There are lots of anchors to choose from: leading and trailing edges, top and bottom edges, center X and center Y, and more.

To try it out, first create a view something like this:

let child = UIView()
child.translatesAutoresizingMaskIntoConstraints = false
child.backgroundColor = .red
view.addSubview(child)

Now we can position that view by activating various anchors. For example, we could pin it to the top and bottom edges of the screen, make it precisely 128 points wide, then center it horizontally:

child.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
child.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
child.widthAnchor.constraint(equalToConstant: 128).isActive = true
child.centerXAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerXAnchor).isActive = true

To explore anchors further, try typing child.anchor and exploring the code completion options.

SAVE 20% ON iOS CONF SG The largest iOS conference in Southeast Asia is back in Singapore for the 5th time in January 2020, now with two days of workshops plus two days of talks on SwiftUI, Combine, GraphQL, and more! Save a massive 20% on your tickets by clicking on this link.

Available from iOS 9.0

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

MASTER SWIFT NOW
Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 5.0/5