问Swift自定义键盘-显示额外的字母弹出在键盘上长按？

EN

let btn: UIButton=UIButton(frame: CGRect(x: 5, y: 70, width: 30, height: 30))
     btn.setTitle("A", for: .normal)
    btn.setTitleColor(UIColor.black, for: .normal);
     self.view.addSubview(btn)

     let longGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPress(sender:)))
longGesture.minimumPressDuration = 1.2
        btn.addGestureRecognizer(longGesture)

  func longPress( sender: Any) {
            
            let longPressGesture = sender as! UILongPressGestureRecognizer

//Only run this code When State Begain
if longPressGesture.state != UIGestureRecognizerState.Began {
            return
     }
// if PopUpView is Already in added than remove and than  add
 if let checkView = self.view.viewWithTag(1001) as? UIView {
         // remove popView
        popUpView .removeFromSuperview()
   }
            
            let tapLocation = longPressGesture.location(in: self.view)
            
            
            popUpView=UIView(frame: CGRect(x: tapLocation.x-10, y: tapLocation.y-65, width: 150, height: 60))
            popUpView.backgroundColor=UIColor.orange
            popUpView.layer.cornerRadius=5
            popUpView.layer.borderWidth=2
            popUpView.tag=1001
            popUpView.layer.borderColor=UIColor.black.cgColor
            
            let btn0: UIButton=UIButton(frame: CGRect(x: 5, y: 5, width: 30, height: 30))
            btn0.setTitle("A1", for: .normal)
            btn0.setTitleColor(UIColor.black, for: .normal);
            btn0.layer.borderWidth=0.5
            btn0.layer.borderColor=UIColor.lightGray.cgColor
            
            popUpView.addSubview(btn0)
            
            let btn1: UIButton=UIButton(frame: CGRect(x: 35, y: 5, width: 30, height: 30))
            btn1.setTitle("A2", for: .normal)
            btn1.setTitleColor(UIColor.black, for: .normal);
            btn1.layer.borderWidth=0.5
            btn1.layer.borderColor=UIColor.lightGray.cgColor
            
            popUpView.addSubview(btn1)
            
            let btn2: UIButton=UIButton(frame: CGRect(x: 70, y: 5, width: 30, height: 30))
            btn2.setTitle("A2", for: .normal)
            btn2.setTitleColor(UIColor.black, for: .normal);
            btn2.layer.borderWidth=0.5
            btn2.layer.borderColor=UIColor.lightGray.cgColor
            
            popUpView.addSubview(btn2)
            
            btn0.addTarget(self, action: #selector(self.buttonAction(sender:)),
                             for: UIControlEvents.touchUpInside)
            btn1.addTarget(self, action: #selector(self.buttonAction(sender:)),
                           for: UIControlEvents.touchUpInside)
            btn2.addTarget(self, action: #selector(self.buttonAction(sender:)),
                           for: UIControlEvents.touchUpInside)
     
             self.view.addSubview(popUpView)
            
           
        }

      func buttonAction( sender: Any) {
            
            // Do your Stuff Here
            
            
            //Than remove popView
            popUpView .removeFromSuperview()
        }