Swift/OC 为View或ImageView设置聊天气泡的小三角

Swift代码(同步到Swift3.0)

---

override func viewDidLoad() {
        super.viewDidLoad()

        let showView = UIImageView.init(frame: CGRect(x: 100, y: 100, width: 100, height: 100))


        showView.image = UIImage(named: "Snip20161312_3")
        showView.layer.mask