title: How I Detect if a NSUrlSession exist iOS
body: <p>I have a TableView which pushes a viewController. This viewController creates a <code>NSURLSession</code> to download in a separate process. but can I detect if the session exists in the event that the user re-enters the viewController before the process is finished?</p>
  
  <pre><code>NSString *name= [NSString stringWithString:[self.myObject objectForKey:@"title"]];
  self.conf = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:name];
  self.backgroundDownloadSession = [NSURLSession sessionWithConfiguration:self.conf
                                                                     delegate:self
                                                                delegateQueue:self.delegateQueue
  </code></pre>