Round Top Corners of a UIButton in Swift

Question

I know I can round all four corners using:

 myBtn.layer.cornerRadius = 8
 myBtn.layer.masksToBounds = true

Since I only want to round two,

Answer 1

Swift 4: For latest iOS 11 onwards

override func viewDidLoad() {
    super.viewDidLoad()

    if #available(iOS 11.0, *) {
        self.viewToRound.clipsToBounds = true
        viewToRound.layer.cornerRadius = 20
        viewToRound.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
    } else {
        // Fallback on earlier versions
    }
}

Earlier iOS (10,9 etc) Versions (works for iOS 11 too)

override func viewDidLayoutSubviews() {
    self.viewToRound.clipsToBounds = true
    let path = UIBezierPath(roundedRect: viewToRound.bounds,
                            byRoundingCorners: [.topRight, .topLeft],
                            cornerRadii: CGSize(width: 20, height: 20))

    let maskLayer = CAShapeLayer()

    maskLayer.path = path.cgPath
    viewToRound.layer.mask = maskLayer
}