title: Retrieve Alamofire estimatedTimeRemaining & file downloaded size
body: <p>I am trying to download a file using Alamofire. To show progress, i am using downloadProgress from alamofire. I got the progress percentage from it. But i need to show the total Mb/Kb downloaded so far and estimated time remaining as well. Here is my code:</p>
  
  <pre><code>AF.download("http://ipv4.download.thinkbroadband.com/200MB.zip",
                  method: .get,
                  parameters: nil,
                  encoding: URLEncoding.default,
                  headers: nil,
                  interceptor:nil,
                  to: destination)
                  .downloadProgress { progress in
                      self.postProgress(progress: progress)
                  }
                  .responseData { response in
                      if let data = response.result.value {
  //                        let image = UIImage(data: data)
                      }
              }
  </code></pre>
  
  <p>Posting the progress using notification</p>
  
  <pre><code>func postProgress(progress: Progress) {
          NotificationCenter.default.post(name: .DownloadProgress, object: progress)
      }
  </code></pre>
  
  <p>Showing my progress using the following codes</p>
  
  <pre><code>if let progress = notification.object as? Progress {
              progressBar.setProgress(Float(progress.fractionCompleted), animated: true)
              progressInNumberView.text = "\(Int64(progress.fractionCompleted*100))%"
              remianingView.text = "\(progress.fileCompletedCount) / \(progress.fileTotalCount)"
              if let estimatedTimeRemaining = progress.estimatedTimeRemaining {
  
                  remianingView.text = format(estimatedTimeRemaining)
              }
          }
  </code></pre>
  
  <p>I am getting progress.fractionCompleted perfectly. But progress.estimatedTimeRemaining, progress.fileCompletedCount and progress.fileTotalCount is always nil. </p>