class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    
        //创建视图
        let redV = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
        
        //设置视图的背景颜色
        redV.backgroundColor = UIColor.red;
        
        //添加到当前页面
        view.addSubview(redV);
        redV.center = view.center;
    
        
        let btn = UIButton(type: .contactAdd);
        redV .addSubview(btn);

        
        btn.addTarget(self, action: #selector(btnClicked), for: .touchUpInside);
        
    }

    @objc func btnClicked()->String{
        print(#function);
        return "111";
    }
}