title: How to use special characters \n in URL
body: <p>I have POST request:</p>
  
  <pre><code>init (url: String,arg: String) {
      self.responseString = nil
      var request = URLRequest(url: URL(string: url)!)
      request.httpMethod = "POST"
      let postString = arg
      request.httpBody = postString.data(using: .utf8)
      let task = URLSession.shared.dataTask(with: request) {
          data, response, error in
          guard let data = data, error == nil else {                                                 
              print("error=\(error)")
              self.responseString = nil
              return
          }
          if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {           //
              self.responseString = nil
          } else {
          self.responseString = String(data: data, encoding: .utf8)
          }
      }
      task.resume()
      }
  </code></pre>
  
  <p>When arg have a character \n, half arg text is lost. How fix this problem? </p>