ios - 如何使用 texfield 扩展来限制用户输入特殊字符？

Question

我想使用 UITextField 扩展来限制用户不要输入特殊字符。我使用了下面的代码，但 UItextfield 不允许我定义商店属性。所以我不知道在哪里定义特殊字符集。

extension UITextField:UITextFieldDelegate {


    var allowSpecialCharecters:Bool {
        get {
            return self.allowSpecialCharecters
        }
        set {
           self.allowSpecialCharecters = newValue
        }
    }



    public func shouldChangeText(in range: UITextRange, replacementText text: String) -> Bool {


        if !allowSpecialCharecters {

            let set = NSCharacterSet(charactersIn: notAllowedCharacters);
            let inverted = set.inverted;

            let filtered = text.components(separatedBy: inverted).joined(separator: "")
            print("String Filtered: \(filtered)")
            return filtered != text;

        } else {
            return true
        }

    }
}

Answer 1

首先，UITextFieldDelegate 有一个特定方法，允许或不允许用户输入所需的字符:func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool。

换句话说，通过实现此方法，您可以控制用户可以输入的字符、数字......以下是我通过几个示例实现的方法:

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let text = textField.text else { return true }
    let candidate = (text as NSString).replacingCharacters(in: range, with: string)
    switch textField.tag {
    //Restrict to only have 2 number digits and max 23 for hours for UITextfields having tags 1, 3, 5 and 7
    case 1, 3, 5, 7:
        return textField.hasHourPattern(in: candidate, range: NSRange(location: 0, length: candidate.characters.count))
    //Restrict to only have 2 number digits and max 59 for minutes fr UITextFields having tags with 2, 4, 6 and 8
    case 2, 4, 6, 8:
        return textField.hasMinutePattern(in: candidate, range: NSRange(location: 0, length: candidate.characters.count))
    //Restrict to have 3 digits max for interger part then . and 2 digits for decimal part for UITextField having tag 9 
    case 9:
        return textField.hasTauxPattern(in: candidate, range: NSRange(location: 0, length: candidate.characters.count))
    default:
        return true
    }
}

然后，我扩展 UITextField 类来创建 3 个函数，以使用正则表达式检查输入表达式。我控制输入的表达式是否与特定模式匹配:

extension UITextField {
// Patterns function
// If has hour pattern : 0 to 23 include

  func hasHourPattern(in string: String, options: NSRegularExpression.MatchingOptions = [], range: NSRange) -> Bool {
    let regex = try? NSRegularExpression(pattern: "^(?:[0-9]|0[0-9]|1[0-9]|2[0-3]|)$", options: [])
    return regex?.firstMatch(in: string, options: [], range: NSRange(location: 0, length: string.characters.count)) != nil
  }

// If has minute pattern : 0 to 59 include

  func hasMinutePattern(in string: String, options: NSRegularExpression.MatchingOptions = [], range: NSRange) -> Bool {
    let regex = try? NSRegularExpression(pattern: "^(?:[0-9]|0[0-9]|1[0-9]|2[0-9]|3[0-9]|4[0-9]|5[0-9]|)$", options: [])
    return regex?.firstMatch(in: string, options: [], range: NSRange(location: 0, length: string.characters.count)) != nil
  }

// If has taux pattern : 3 decimals . and 2 decimals

  func hasTauxPattern(in string: String, options: NSRegularExpression.MatchingOptions = [], range: NSRange) -> Bool {
    let regex = try? NSRegularExpression(pattern: "^\\d{0,3}(\\.\\d{0,2})?$", options: [])
    return regex?.firstMatch(in: string, options: [], range: NSRange(location: 0, length: string.characters.count)) != nil
  }
  ...//Create whatever function to check a pattern you want
}

此外，您还可以使用名为 keyboardType 的 UITextfield 属性，通过显示所需的键盘类型来指示您想要的字符类型。