title: How to set NSURLRequest cache expiration?
body: <p>I'm using AFNetworking and need to cache data in one response for a several minutes. So I set NSUrlCache in app delegate and then in my request setting up it:</p>
  
  <pre><code>NSMutableURLRequest *request = //obtain request; 
  request.cachePolicy = NSURLRequestReturnCacheDataElseLoad;
  </code></pre>
  
  <p>How then set expiration date: if the data was loaded more than n minutes ago, ask response from server and not from disk? </p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Assume that server doesn't support caching, I need to manage it in code. </p>