@IBAction函数来查看DidLoad

Question

我试图从后台视图向ViewController.swift添加一个@IBAction，以响应Touch Down事件。我的IBAction将使序列为黑色->白色->浅灰色->深灰色->红色->黑色。当用户点击屏幕时，此序列应无限期重复。为了我自己，我不知道为什么它不起作用。

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.black
        self.changeBackground(self)
        // Do any additional setup after loading the view, typically from a nib.
    }

    @IBAction func changeBackground(_ sender: Any) {

        let button : UIButton = sender as! UIButton
            button.isSelected = !button.isSelected

            if (button.isSelected && self.view.backgroundColor  == UIColor.black){
                self.view.backgroundColor = UIColor.white
            }

            if (button.isSelected && self.view.backgroundColor  == UIColor.white){
                self.view.backgroundColor = UIColor.lightGray
            }

            if (button.isSelected && self.view.backgroundColor  == UIColor.lightGray){
                self.view.backgroundColor = UIColor.darkGray
            }

            if (button.isSelected && self.view.backgroundColor  == UIColor.darkGray){
                self.view.backgroundColor = UIColor.red
            }

            if (button.isSelected && self.view.backgroundColor  == UIColor.red){
                self.view.backgroundColor = UIColor.black
            }

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}