title: Reachability vs NSURLSession response to detect internet connection
body: <p>I'm building out error cases for my API calls and would like to check for a condition when an internet connection in not available.</p>
  
  <p><code>dataTaskWithRequest</code> seems to handle this just fine and returns an <code>NSError</code> with code -1009 with a description of no internet connection. I doesn't have to wait for the request to time out.</p>
  
  <p>In what instances would I want to use the Reachability Framework instead?
  Thanks</p>