限制textField中的字符和字符长度（_：shouldChangeCharactersInRange：replacementString :)(Limiting characters and character length in textField(_:shouldChangeCharactersInRange:replacementString:))

 我的应用中有一个用户名textField，我想限制为24个字符，不允许“|” 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，但是我无法将这两者组合到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
  }
 
 我真的很感激有关如何将这两者结合到textField（_：shouldChangeCharactersInRange：replacementString :)的任何建议 

I have a username textField in my app that I want to limit to 24 characters and not allow "|" a pipe in the username.
 
I am able to do each of these individually with the code below but I have having trouble combining these both into textField(_:shouldChangeCharactersInRange:replacementString:).
 
This code is successfully disallows a "|" in the username field.
 
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
    }
  }
 
This code successfully limits the username field to 24 characters.
 
  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
  }
 
I would really appreciate any advice on how to combine these both into textField(_:shouldChangeCharactersInRange:replacementString:)

原文：https://stackoverflow.com/questions/37366639