        // Show the message.
        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        self.present(alert, animated: true, completion: nil)
        return
    }
    
    @IBAction func onSignClick(_ sender: UIButton)
    {
        var alert: UIAlertController = UIAlertController(title: "Secure Key Sample", message: "Test string '\(signingString)' signed.", preferredStyle: .alert)
        