How to round only specific corners using maskedCorners

Swift version: 5.1

Paul Hudson @twostraws May 28th 2019

You can set the cornerRadius property of any UIView to have its edges rounded, but by default that rounds all corners at the same time. If you want only some corners to be rounded, you should set the layer’s maskedCorners property to be an array of the corners you want – it’s an option set, so you can set one or many depending on your needs.

For example, this code rounds the top-left and bottom-right corners of a view, leaving the other two square:

let redBox = UIView(frame: CGRect(x: 100, y: 100, width: 128, height: 128))
redBox.backgroundColor = .red
redBox.layer.cornerRadius = 25
redBox.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMaxYCorner]
view.addSubview(redBox)

Available from iOS 11.0