Ios 防止UITextField在更改第一响应程序时获取值

我有四个UITextField，每个字段代表OTP的一个位数。我希望控件在用户键入代码时切换到连续文本字段。我的实现如下

extension FillSignUpCodeController: UITextFieldDelegate {

    func textFieldDidBeginEditing(_ textField: UITextField) {
        textField.text = ""
    }

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let inputString = (textField.text! as NSString).replacingCharacters(in: range, with: string)

        if inputString.count == 1 {
            switch textField {

            case textFieldCodeFirstDigit:
                textFieldCodeFirstDigit.text = inputString
                textFieldCodeFirstDigit.resignFirstResponder()
                textFieldCodeSecondDigit.becomeFirstResponder()

            case textFieldCodeSecondDigit:
                textFieldCodeSecondDigit.text = inputString
                textFieldCodeSecondDigit.resignFirstResponder()
                textFieldCodeThirdDigit.becomeFirstResponder()

            case textFieldCodeThirdDigit:
                textFieldCodeThirdDigit.text = inputString
                textFieldCodeThirdDigit.resignFirstResponder()
                textFieldCodeFourthDigit.becomeFirstResponder()

            case textFieldCodeFourthDigit:
                textFieldCodeFourthDigit.text = inputString
                textFieldCodeFourthDigit.resignFirstResponder()

            default:
                return false
            }
        }
        return true
    }
}

使用这段代码，当用户键入第一个数字时，第一个文本字段接受输入值并将控件移动到下一个文本字段。但是，第二个文本字段采用第一个数字的值。在更改firstResponder后，我尝试将文本设置为空，但没有成功。如何解决此问题？谢谢。

由于

textField（\uu:shouldChangeCharactersIn:replacementString:）

在文本字段中出现文本之前执行，因此您应该将代码放入一个方法中，该方法在文本已经更改时调用

您应该观察文本字段的更改，并在那里执行响应者更改代码。你可以找到更多的信息

此外，在更换第一响应者之前辞职是多余的，您不需要这样做

单独处理每个文本字段也是非常多余的。我建议将文本字段包含在数组中并对其进行迭代。

由于

文本字段（uuu:shouldChangeCharactersIn:replacementString:）

在文本字段中出现文本之前执行，因此应将代码放入一个方法中，该方法在文本发生更改时调用

您应该观察文本字段的更改，并在那里执行响应者更改代码。你可以找到更多的信息

此外，在更换第一响应者之前辞职是多余的，您不需要这样做

---

单独处理每个文本字段也是非常多余的。我建议将文本字段包含在数组中，并对其进行迭代。

应该在填充文本字段之前调用ChangeCharactersRange。您可以通过以下方式完成：

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

为viewDidLoad（）中的所有文本字段在行上方写入

---

这将起作用。

在填充文本字段之前调用shouldChangeCharactersRange。您可以通过以下方式完成：

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

为viewDidLoad（）中的所有文本字段在行上方写入

---

这将起作用

根据@4kman和@Rahul Dasgupta的回答，我实施了以下措施：

FillUpCodeViewController.swift

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldCodeFirstDigit,
                            textField2: textFieldCodeSecondDigit,
                            textField3: textFieldCodeThirdDigit,
                            textField4: textFieldCodeFourthDigit)
}

func setupArrrayofTextFields(textField1: UITextField, textField2: UITextField,
                             textField3: UITextField, textField4: UITextField) {

    arrayOftextFields = [textField1, textField2, textField3, textField4]
    for textField in arrayOftextFields {
        textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
    }
}

@objc func textFieldDidChange(textField: UITextField) {
    guard textField.text?.count == 0 else {
        let index: Int = arrayOftextFields.index(of: textField)!
        guard index == (arrayOftextFields.count-1) else {
            arrayOftextFields[index+1].becomeFirstResponder()
            return
        }
        textField.resignFirstResponder()
        return
    }
}

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldRecoveyCodeFirstDigit,
                            textField2: textFieldRecoveyCodeSecondDigit,
                            textField3: textFieldRecoveyCodeThirdDigit,
                            textField4: textFieldRecoveyCodeFourthDigit)
}

同样，在我必须实现恢复代码提交的viewcontroller中，我简单地继承了FillUpCodeViewController类

RecoveryViewController.swift

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldCodeFirstDigit,
                            textField2: textFieldCodeSecondDigit,
                            textField3: textFieldCodeThirdDigit,
                            textField4: textFieldCodeFourthDigit)
}

func setupArrrayofTextFields(textField1: UITextField, textField2: UITextField,
                             textField3: UITextField, textField4: UITextField) {

    arrayOftextFields = [textField1, textField2, textField3, textField4]
    for textField in arrayOftextFields {
        textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
    }
}

@objc func textFieldDidChange(textField: UITextField) {
    guard textField.text?.count == 0 else {
        let index: Int = arrayOftextFields.index(of: textField)!
        guard index == (arrayOftextFields.count-1) else {
            arrayOftextFields[index+1].becomeFirstResponder()
            return
        }
        textField.resignFirstResponder()
        return
    }
}

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldRecoveyCodeFirstDigit,
                            textField2: textFieldRecoveyCodeSecondDigit,
                            textField3: textFieldRecoveyCodeThirdDigit,
                            textField4: textFieldRecoveyCodeFourthDigit)
}

---

根据@the4kman和@Rahul Dasgupta的回答，我实施了以下内容：

FillUpCodeViewController.swift

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldCodeFirstDigit,
                            textField2: textFieldCodeSecondDigit,
                            textField3: textFieldCodeThirdDigit,
                            textField4: textFieldCodeFourthDigit)
}

func setupArrrayofTextFields(textField1: UITextField, textField2: UITextField,
                             textField3: UITextField, textField4: UITextField) {

    arrayOftextFields = [textField1, textField2, textField3, textField4]
    for textField in arrayOftextFields {
        textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
    }
}

@objc func textFieldDidChange(textField: UITextField) {
    guard textField.text?.count == 0 else {
        let index: Int = arrayOftextFields.index(of: textField)!
        guard index == (arrayOftextFields.count-1) else {
            arrayOftextFields[index+1].becomeFirstResponder()
            return
        }
        textField.resignFirstResponder()
        return
    }
}

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldRecoveyCodeFirstDigit,
                            textField2: textFieldRecoveyCodeSecondDigit,
                            textField3: textFieldRecoveyCodeThirdDigit,
                            textField4: textFieldRecoveyCodeFourthDigit)
}

同样，在我必须实现恢复代码提交的viewcontroller中，我简单地继承了FillUpCodeViewController类

RecoveryViewController.swift

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldCodeFirstDigit,
                            textField2: textFieldCodeSecondDigit,
                            textField3: textFieldCodeThirdDigit,
                            textField4: textFieldCodeFourthDigit)
}

func setupArrrayofTextFields(textField1: UITextField, textField2: UITextField,
                             textField3: UITextField, textField4: UITextField) {

    arrayOftextFields = [textField1, textField2, textField3, textField4]
    for textField in arrayOftextFields {
        textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
    }
}

@objc func textFieldDidChange(textField: UITextField) {
    guard textField.text?.count == 0 else {
        let index: Int = arrayOftextFields.index(of: textField)!
        guard index == (arrayOftextFields.count-1) else {
            arrayOftextFields[index+1].becomeFirstResponder()
            return
        }
        textField.resignFirstResponder()
        return
    }
}

override func viewDidLoad() {

    setupArrrayofTextFields(textField1: textFieldRecoveyCodeFirstDigit,
                            textField2: textFieldRecoveyCodeSecondDigit,
                            textField3: textFieldRecoveyCodeThirdDigit,
                            textField4: textFieldRecoveyCodeFourthDigit)
}