on single tap UIBarButton display toast and on double tap back action need to perform

Question

I have an UIBarButton in navigation bar, while clicking on back button (first tap) i need to display toast (like warning), on double tap i need to exit from the page in swift,

Answer 1

override func viewDidLoad() {
        super.viewDidLoad()

        self.navigationItem.hidesBackButton = true
        let button = UIButton(type: .system)
        button.frame = CGRect(x: 0, y: 0, width: 80, height: 40)
        button.setTitle("Back", for: .normal)

        //Gesture Recognizer
        let singleTap = UITapGestureRecognizer(target: self, action: #selector(handleSingleTap))
        singleTap.numberOfTapsRequired = 1
        let doubleTap = UITapGestureRecognizer(target: self, action: #selector(handleDoubleTap))
        doubleTap.numberOfTapsRequired = 2
        button.addGestureRecognizer(singleTap)
        button.addGestureRecognizer(doubleTap)
        singleTap.require(toFail: doubleTap)

        let barButton = UIBarButtonItem(customView: button)
        self.navigationItem.leftBarButtonItem = barButton
    }
    @objc func handleSingleTap(sender: UITapGestureRecognizer? = nil) {
        let toastLabel = UILabel(frame: CGRect(x: 20, y: self.view.frame.size.height-100, width: 350, height: 35))
        toastLabel.backgroundColor = UIColor.black.withAlphaComponent(0.6)
        toastLabel.textColor = UIColor.white
        toastLabel.textAlignment = .center;
        toastLabel.font = UIFont(name: "Montserrat-Light", size: 12.0)
        toastLabel.text = "demo"
        toastLabel.alpha = 1.0
        toastLabel.layer.cornerRadius = 10;
        toastLabel.clipsToBounds  =  true
        self.view.addSubview(toastLabel)
        UIView.animate(withDuration: 2.0, delay: 0.1, options: .curveEaseOut, animations: {
            toastLabel.alpha = 0.0
        }, completion: {(isCompleted) in
            toastLabel.removeFromSuperview()
        })
        print("Single Tap detected")
    }
    @objc func handleDoubleTap(sender: UITapGestureRecognizer? = nil) {
        print("Double Tap detected")
    }