Question

我已经设置了4个TextField并通过textFieldDidChange连接了它们。现在假设我输入了错误的验证，我希望能够再次选择TextField并清除所有最后的输入。我在Swift 3中尝试了didBeginEditing，但它不起作用，因为它只清除了一个TextField而不是全部四个TextField。请帮忙。

import UIKit

class verificationVC: UIViewController,UITextFieldDelegate, UITextViewDelegate  {

    @IBOutlet weak var codefirstText: UITextField!
    @IBOutlet weak var codesecondText: UITextField!
    @IBOutlet weak var codethirdText: UITextField!
    @IBOutlet weak var codefourthText: UITextField!

    func textFieldDidBeginEditing(textField: UITextField)
    {
        codefirstText.text = ""
        codesecondText.text = ""
        codethirdText.text = ""
        codefourthText.text = ""

        if (codefirstText.text != nil)
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codesecondText.text != nil)
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codethirdText.text != nil)
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codefourthText.text != nil)
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
    }

    func textFieldDidChange (textfield: UITextField)
    {
        let text = textfield.text

        if text?.utf16.count == 1
        {
            switch textfield {
            case codefirstText:
                codesecondText.becomeFirstResponder()
            case codesecondText:
                codethirdText.becomeFirstResponder()
            case codethirdText:
                codefourthText.becomeFirstResponder()
            case codefourthText:
                codefourthText.resignFirstResponder()
            default:
                break
        }
    }

Answer 1

由于在Swift中输入的类型，字符串不能是nil。您是否尝试使用空字符串而不是nil值来控制文本字段值：

func textFieldDidBeginEditing(textField: UITextField)
    {
        codefirstText.text = ""
        codesecondText.text = ""
        codethirdText.text = ""
        codefourthText.text = ""

        if (codefirstText.text != "")
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codesecondText.text != "")
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codethirdText.text != "")
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }
        else if (codefourthText.text != "")
        {
            codefirstText.text = ""
            codesecondText.text = ""
            codethirdText.text = ""
            codefourthText.text = ""
        }

    }

如何在开始编辑时清除所有TextField或在Swift 3中选择TextField？

1 个答案: