iOS Swift监听键盘通知和获取距离底部间距

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首先在viewDidLoad()方法中：分别添加键盘即将弹出、即将消失和frame修改的通知

//键盘监听
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
        
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)

2.实现键盘监听事件

/*键盘弹出*/
    @objc func keyboardWillShow(_ showNoti:Notification){
        
        KeyboardFrame = (showNoti.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        
        let keyboardY = KeyboardFrame.origin.y
        if keyboardY <= self.view.center.y + self.alertView.frame.height/2{
            
            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1.0, initialSpringVelocity: 15.0, options: .curveLinear, animations: {
                
                if (self.hasTextFields == true && self.firstShow == false){
                    
                    self.hasTextFields = false;
                    
                }
                    
                self.alertView.frame.origin.y = keyboardY - self.alertView.frame.height - 15
                self.contentView.frame = self.alertView.bounds
                
                
            }, completion: nil)
            
        }
        
    }
    
    /*键盘隐藏*/
    @objc func keyboardWillHide(_ hideNoti:Notification){
        
        UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1.0, initialSpringVelocity: 5.0, options: .curveEaseOut, animations: {
            
            if self.contentViewFrameNormal != nil{
                
                self.alertView.frame = self.contentViewFrameNormal
                
            }
            
            self.alertView.center = self.view.center
            self.contentView.frame = self.alertView.bounds
            
        }, completion: nil)
        
    }

3.收起键盘的事件

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        //收起键盘
        textField.resignFirstResponder()
        return true
    }

4.移除通知

deinit {
        NotificationCenter.default.removeObserver(self)
        print("AntScanCodeViewController deinit")
    }