按钮操作未执行

Question

我正在创建一个带按钮的可滚动菜单。使用按钮标签创建菜单，但是当我单击按钮时，不执行操作。我使用以下代码：

for i in 0...4 {

        var aButton = UIButton(type: .custom)
        aButton.setImage(UIImage(named: "Hello"), for: .normal)
       aButton.frame = CGRect(x: xCoord, y: yCoord, width: buttonWidth, height: buttonHeight)
        aButton.tintColor = UIColor.white
        aButton.tag = i
        aButton.addTarget(self, action: #selector(scrollButAction(sender:)), for: .touchUpInside)
        var aLabel = UILabel(frame: CGRect(x: xCoord,y: 40, width: buttonWidth, height: 24))
        aLabel.text = labArr[i]
        aLabel.textColor = UIColor.white
        aLabel.adjustsFontSizeToFitWidth = true
        aLabel.font = UIFont.init(name: "HelveticaNeue-Light", size: 14)
        scrollView?.addSubview(aButton)
        scrollView?.addSubview(aLabel)

        xCoord += buttonWidth + buffer

    }

我的scrollButAction函数是：

func scrollButAction(sender: UIButton) {
    switch sender.tag {

    case 0:

        print("Hello #0")

    case 1:

       print("Hello #1")

    case 2:

       print("Hello #2")

    case 3:

        print("Hello #3")

    case 4:


        print("Hello #4")

    default:

        print("default")

    }
}