ios - 限制文本字段中的字符和字符长度(_ :shouldChangeCharactersInRange:replacementString:)

Question

我的应用程序中有一个用户名文本字段，我想将其限制为 24 个字符并且不允许使用“|”用户名中的管道。

我可以使用下面的代码单独执行这些操作，但是我无法将它们组合到 textField(_:shouldChangeCharactersInRange:replacementString:) 中。

此代码成功禁止“|”在用户名字段中。

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

    if textField === usernameField {
      // Create an `NSCharacterSet` set
      let set = NSCharacterSet(charactersInString:"|")

      // At every character in this "set" contained in the string,
      // split the string up into components which exclude the characters
      // in this inverse set
      let components = string.componentsSeparatedByCharactersInSet(set)

      // Rejoin these components
      let filtered = components.joinWithSeparator("")

      // If the original string is equal to the filtered string, i.e. if no
      // characters were present to be eliminated, the input is valid
      // and the statement returns true; else it returns false
      return string == filtered
    } else {
      return true
    }
  }

此代码成功地将用户名字段限制为 24 个字符。

  func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    // Added to limit title to <= 40 characters
    guard let text = meetupTitleTextField.text else { return true }

    let newLength = text.utf16.count + string.utf16.count - range.length
    return newLength <= 48 // Bool
  }

如果有任何关于如何将它们组合到 textField(_:shouldChangeCharactersInRange:replacementString:) 中的建议，我将不胜感激

Answer 1

试试这个:

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    if textField == usernameField, let text = textField.text {
        let newLength = text.characters.count + string.characters.count - range.length
        return newLength <= 48 && !string.containsString("|")
    }

    return true
}