         let checkImageView_bottom = NSLayoutConstraint(item: checkImageView, attribute: .bottom, relatedBy: .equal, toItem: rememberBoxBtn, attribute: .bottom, multiplier: 1.0, constant: 0)
         backGroundImageView.addConstraint(checkImageView_bottom)
         checkImageView.isHidden = true
+        
+        //用户名的tableView下拉tableView
+        userNamesTableView = UITableView(frame: CGRect.zero, style: .plain)
+        userNamesTableView.translatesAutoresizingMaskIntoConstraints = false
+        backGroundImageView.addSubview(userNamesTableView)
+        userNamesTableView.delegate = self
+        userNamesTableView.dataSource = self
+    }
+    //table的数据源
+    func numberOfSections(in tableView: UITableView) -> Int {
+        return 1
+    }
+    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        return 3
+    }
+//    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+//        
+//    }
+    //tableView代理方法
+    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        
     }
     //记住按钮的点击事件
     func rememberBtnClicked() {

        backGroundImageView.addConstraint(passwordIconimageV_width)
        
        //用户名输入textfield
        let usernameTextField = UITextField()
        usernameTextField.placeholder = "请输入用户名"
        //        usernameTextField.backgroundColor = UIColor.green
        usernameTextField.translatesAutoresizingMaskIntoConstraints = false
        userNameBGView.addSubview(usernameTextField)
        let usernameTextField_leading = NSLayoutConstraint(item: usernameTextField, attribute: .leading, relatedBy: .equal, toItem: userNameIconimageV, attribute: .trailing, multiplier: 1.0, constant: 5)
        userNameBGView.addConstraint(usernameTextField_leading)

        arrowBtn.addTarget(self, action: #selector(ViewController.arrowBtnClicked), for: UIControlEvents.touchUpInside)
        
        //密码输入textfield
        passwordTextField = UITextField()
        passwordTextField.placeholder = "请输入密码"
        //        passwordTextField.backgroundColor = UIColor.green
        passwordTextField.translatesAutoresizingMaskIntoConstraints = false
