title: NSURLConnection didFailWithError "unsupported URL" for alphanumeric link
body: <p>I am trying to download a JPG file using <code>NSURLConnection</code>. The file fails to load and the delegate <code>didFailWithError</code> states in the <code>error</code> object: <strong>unsupported URL</strong></p>
  
  <p>My URL is alphanumeric like this example:</p>
  
  <pre><code>http://www.mySite.com/myFolder/123456789_123456789_12-34-56_1234_abcd.jpg
  </code></pre>
  
  <p>I also tried to use <code>CFURLCreateStringByAddingPercentEscapes</code> to encode the underscore and the minus sign but this didn't help. If I copy/paste the link from the code to my web browser it opens normally.</p>
  
  <p>What could be the problem?</p>