How to center a view in its container

Swift version: 5.10

Paul Hudson @twostraws May 28th 2019

There are two ways to center one UIView inside another, depending on whether you use Auto Layout.

If you don’t use Auto Layout, it’s only one line of code:

childView.center = parentView.center

That sets the position once, so it won’t update when your user rotates their device or if they use something like Slide Over to change the size of your app.

If you’re using Auto Layout, you can center your child view inside its parent like this:

childView.centerXAnchor.constraint(equalTo: parentView.centerXAnchor).isActive = true
childView.centerYAnchor.constraint(equalTo: parentView.centerYAnchor).isActive = true

Those constraints will automatically update as the available space changes.