Cut a UIImage into a circle

Question

I want to cut a UIImage into a circle so that I can then use it as an annotation. Every answer on this site that I\'ve found describes creating an UIImage

Answer 1

Xcode 11 • Swift 5.1 or later

edit/update: For iOS10+ We can use UIGraphicsImageRenderer. For older Swift syntax check edit history.

extension UIImage {
    var isPortrait:  Bool    { size.height > size.width }
    var isLandscape: Bool    { size.width > size.height }
    var breadth:     CGFloat { min(size.width, size.height) }
    var breadthSize: CGSize  { .init(width: breadth, height: breadth) }
    var breadthRect: CGRect  { .init(origin: .zero, size: breadthSize) }
    var circleMasked: UIImage? {
        guard let cgImage = cgImage?
            .cropping(to: .init(origin: .init(x: isLandscape ? ((size.width-size.height)/2).rounded(.down) : 0,
                                              y: isPortrait  ? ((size.height-size.width)/2).rounded(.down) : 0),
                                size: breadthSize)) else { return nil }
        let format = imageRendererFormat
        format.opaque = false
        return UIGraphicsImageRenderer(size: breadthSize, format: format).image { _ in
            UIBezierPath(ovalIn: breadthRect).addClip()
            UIImage(cgImage: cgImage, scale: format.scale, orientation: imageOrientation)
            .draw(in: .init(origin: .zero, size: breadthSize))
        }
    }
}

Playground Testing

let profilePicture = UIImage(data: try! Data(contentsOf: URL(string:"http://i.stack.imgur.com/Xs4RX.jpg")!))!
profilePicture.circleMasked

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