How to position a view using Auto Layout anchors
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 = trueTo explore anchors further, try typing child.anchor and exploring the code completion options.
Available from iOS 9.0
Did this solution work for you? Please pass it on!
Other people are reading…
- How to make a UIView fill the screen using Auto Layout anchors
- How to read the interface orientation: portrait or landscape?
- How to let users tap on a UITableViewCell while editing is enabled
- How to add a flexible space to a UIBarButtonItem
- How to scale, stretch, move and rotate UIViews using CGAffineTransform
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
