title: Set Limit for TextField characters in RxSwift
body: <p>I want to set a limit for characters in a textFiled using RxSwift, 
  may be i can benefit from <code>Scan</code> operator but i don't know how to use it in this case ,</p>
  
  <p>I want my resulting code to behave as same as implementing it in <code>shouldChangeCharacterInRage</code> method:</p>
  
  <pre><code>   func textField(_ textField: UITextField,
                     shouldChangeCharactersIn range: NSRange,
                     replacementString string: String)
          -&gt; Bool {
              if textField == baseTextFiled{
                  let enteredString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
                  if enteredString.count &gt; limit{ // limit defined previously
                      return false
                  }
              }
              return true
      }
  </code></pre>
  
  <p>Any help?</p>