我试图检查当一个文本字段发生变化时,等效于textView - textViewDidChange的函数,到目前为止我已经做到了这一点:

  func textFieldDidBeginEditing(textField: UITextField) {
        if self.status.text == "" && self.username.text == "" {
            self.topRightButton.enabled = false
        } else {   
            self.topRightButton.enabled = true
        }
    }

哪种类型的工作,但topRightButton一经文本字段被按下就被启用,我想它只在文本实际输入时才被启用?


当前回答

斯威夫特5.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: .editingChanged)

及处理方法:

@objc func textFieldDidChange(_ textField: UITextField) {

}

斯威夫特4.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

及处理方法:

@objc func textFieldDidChange(_ textField: UITextField) {

}

斯威夫特3.0

textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)

及处理方法:

func textFieldDidChange(textField: UITextField) { 

}

其他回答

如果不可能将addTarget绑定到你的UITextField,我建议你像上面建议的那样绑定其中一个,并在shouldChangeCharactersIn方法的末尾插入执行代码。

nameTextField.addTarget(self, action: #selector(RegistrationViewController.textFieldDidChange(_:)), for: .editingChanged)

@objc func textFieldDidChange(_ textField: UITextField) {
    if phoneNumberTextField.text!.count == 17 && nameTextField.text!.count > 0 {
        continueButtonOutlet.backgroundColor = UIColor(.green)
    } else {
        continueButtonOutlet.backgroundColor = .systemGray
    }
}

在调用中shouldChangeCharactersIn func。

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    guard let text = textField.text else {
        return true
    }
    let lastText = (text as NSString).replacingCharacters(in: range, with: string) as String

    if phoneNumberTextField == textField {
        textField.text = lastText.format("+7(NNN)-NNN-NN-NN", oldString: text)
        textFieldDidChange(phoneNumberTextField)
        return false
    }
    return true
}

如果你对SwiftUI解决方案感兴趣,这对我来说是有效的:

 TextField("write your answer here...",
            text: Binding(
                     get: {
                        return self.query
                       },
                     set: { (newValue) in
                        self.fetch(query: newValue) // any action you need
                                return self.query = newValue
                      }
            )
  )

我不得不说这不是我的主意,我在这个博客上看到的:SwiftUI绑定:一个非常简单的技巧

你可以通过“shouldchangecharter”委托或者“begin and end”文本字段委托来管理编辑。别忘了设置委托

我设法做到这一点使用“did开始和结束编辑”下面。

//MARK:- TextViewDelegate
extension ViewController: UITextFieldDelegate {
    func textFieldDidEndEditing(_ textField: UITextField) {
        let count = self.tfEmail.text?.count ?? 0
        if textField == self.tfEmail {
            if count == 0{
              //Empty textfield
            }else{
              //Non-Empty textfield
            }
        }
    }
    func textFieldDidBeginEditing(_ textField: UITextField) {
        if textField == self.tfEmail{
            //when user taps on textfield
        }
    }
}

你可以从UITextFieldDelegate中使用这个委托方法。它会随着角色的变化而爆发。

(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)

然而,这只会在更改之前触发(实际上,只有当你从这里返回true时,才会发生更改)。

斯威夫特

斯威夫特4.2

textfield.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)

and

@objc func textFieldDidChange(_ textField: UITextField) {

}

SWIFT 3和SWIFT 4.1

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)

and

func textFieldDidChange(_ textField: UITextField) {

}

斯威夫特2.2

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

and

func textFieldDidChange(textField: UITextField) {
    //your code
}

objective - c

[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

和textFieldDidChange方法是

-(void)textFieldDidChange :(UITextField *) textField{
    //your code
}