Xcode：Swift - 如何在编辑文本字段时使底线边框颜色出现/消失？

Question

我已经为 UITextField 添加了一个扩展，以显示带有颜色的底部边框，这是有效的。但是，我的意图是当用户点击文本字段以编辑文本时出现底部边框，并在完成编辑后消失边框。我已经提到了有关此问题的其他 stackoverflow 问题，但我找不到涉及底部边框和编辑时出现/消失的答案或问题。

extension UITextField {

    func addBottomBorder() {
        let bottomline = CALayer()
        bottomline.frame = CGRect(x: 0,y:self.frame.size.height - 1, width: self.frame.size.width,height: 1)
        bottomline.backgroundColor = UIColor(red: 255.0/255.0, green: 255.0/255.0, blue: 255.0, alpha: 1.0).cgColor
        borderStyle = .none
        self.layer.addSublayer(bottomline)
        self.layer.masksToBounds = true
    }
    
}

我对 swift 和 Ios 开发还很陌生。如果有人可以显示我应该添加到扩展文件中的内容以使边框在编辑时出现和消失，那将会很有帮助。

更新

视图控制器

     func textFieldDidBeginEditing(_ textField: UITextField) {
        movementTextField.addBottomBorder()
        notesTextField.addBottomBorder()
        descriptionTextField.addBottomBorder()
        shotSize.addBottomBorder()
        shotNameTextField.addBottomBorder()
    }
    
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
        movementTextField.removeBottomBorder()
        notesTextField.removeBottomBorder()
        descriptionTextField.removeBottomBorder()
        shotSize.removeBottomBorder()
        shotNameTextField.removeBottomBorder()
        return true
    }
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
            textField.resignFirstResponder()
        }

扩展更新

 extension UITextField {
    
    func addBottomBorder() {
        let bottomline = CALayer()
        bottomline.frame = CGRect(x: 0,y:self.frame.size.height - 1, width: self.frame.size.width,height: 1)
        bottomline.backgroundColor = UIColor(red: 255.0/255.0, green: 255.0/255.0, blue: 255.0, alpha: 1.0).cgColor
        borderStyle = .none
        self.layer.addSublayer(bottomline)
        self.layer.masksToBounds = true
    }
    
    func removeBottomBorder() {
        let removebottomline = CALayer()
        removebottomline.frame = CGRect(x: 0,y:self.frame.size.height - 1, width: self.frame.size.width,height: 1)
        removebottomline.backgroundColor = UIColor(red: 30.0/255.0, green: 30.0/255.0, blue: 30.0, alpha: 1.0).cgColor
        borderStyle = .none
        self.layer.addSublayer(removebottomline)
        self.layer.masksToBounds = true
    }
}

Answer 1

    @IBOutlet var textFieldFirst: UITextField   
    @IBOutlet var textFieldSecond: UITextField          
    
    override func viewDidLoad() {
        super.viewDidLoad()
        textFieldFirst = self      
        textFieldSecond = self
    }
    
    
    func textFieldDidBeginEditing(textField: UITextField!) {    //didBegin method
         if (textFieldFirst = textField)
              {
               textFieldFirst.addBottomBorder()
              }
        // marks rest condition in ifelse or have switch condition 
    
    }
    
    func textFieldShouldEndEditing(textField: UITextField!) -> Bool {  //EndEiditing method
    if (textFieldFirst = textField)
              {
                textFieldFirst.removeBottomBorder()
              }
         // marks rest condition in ifelse or have switch condition 
    
    }
    
    func textFieldShouldReturn(textField: UITextField!) -> Bool {   
      textField.resignFirstResponder()
    
    }

Answer 2

按照以下步骤进行：

@IBOutlet var nameTextField: UITextField    
@IBOutlet var surnameTextField: UITextField    

override func viewDidLoad() {
    super.viewDidLoad()
    nameTextField.delegate = self           
}


func textFieldDidBeginEditing(textField: UITextField!) {    //didBegin method(when you start editing in textfield) 
//To addBorder for specific Textfield just make a if else condition like:
    if textField == nameTextField {
      addBottomBorder()
    }
                                                    
}

func textFieldShouldEndEditing(textField: UITextField!) -> Bool {  //EndEiditing method(when you end editing in textfield) 
  //To removeBorder for specific Textfield just make a if else condition like:
  if textField == nameTextField {
    removeBottomBorder()
   }
  
}