title: NSURLSession delegates not called
body: <p>In the following code, the file downloads just fine. However none of the delegate methods seem to be called as I receive no output whatsoever. the progressView is not updated either. Any idea why?</p>
  
  <pre><code>import Foundation
  import UIKit
  
  class Podcast: PFQueryTableViewController, UINavigationControllerDelegate, MWFeedParserDelegate, UITableViewDataSource, NSURLSessionDelegate, NSURLSessionDownloadDelegate {
  
      func downloadEpisodeWithFeedItem(episodeURL: NSURL) {
  
      var request: NSURLRequest = NSURLRequest(URL: episodeURL)
      let config = NSURLSessionConfiguration.defaultSessionConfiguration()
      let session = NSURLSession(configuration: config, delegate: self, delegateQueue: nil)
  
      var downloadTask = session.downloadTaskWithURL(episodeURL, completionHandler: { (url, response, error) -&gt; Void in
          println("task completed")
          if (error != nil) {
              println(error.localizedDescription)
          } else {
              println("no error")
              println(response)
          }
      })
      downloadTask.resume()
  
  }
  
  func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didResumeAtOffset fileOffset: Int64, expectedTotalBytes: Int64) {
      println("didResumeAtOffset")
  }
  
      func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
            var downloadProgress = Double(totalBytesWritten) / Double(totalBytesExpectedToWrite)
      println(Float(downloadProgress))
      println("sup")
  
      epCell.progressView.progress = Float(downloadProgress)
  }
  
       func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
      println(location)
  
  }
  }
  </code></pre>