go.swift

    @IBAction func go(_ sender: UIButton) {
        if typeTextField.text == "" {
            let controller = UIAlertController(title: "請給我一個數字", message: "輸入數字才可以繼續喔！", preferredStyle: .alert)
            let action = UIAlertAction(title: "了解", style: .default, handler: nil)
            controller.addAction(action)
            present(controller, animated: true, completion: nil)
        } else if chanceNumber > 1 {
            checkAnswer()
        } else {
            let controller = UIAlertController(title: "遊戲結束", message: "正確答案是\(questionNumber)", preferredStyle: .alert)
            let okAction = UIAlertAction(title: "OK", style: .default) { (_) in
                //將剩餘結果畫面顯示在上面
                self.chanceLabel.text = "你已經用完所有機會了！"
                self.typeTextField.text = "\(self.questionNumber)"
                self.rangeLabel.text = "沒猜中！"
                //這邊會將goButton所以起來，必須在playAgain()重新開啟他
                self.goButton.isUserInteractionEnabled = false
            }
            controller.addAction(okAction)
            let replayAction = UIAlertAction(title: "Re-Play", style: .default) { (_) in
                self.playAgain()
            }
            controller.addAction(replayAction)
            present(controller, animated: true, completion: nil)
        }
    }