title: Alamofire Image: Fetch Image from AutoPurgingImageCache after af_setImageWithURL()
body: <p>I use AlamofireImage in my project. I use <code>someImageView.af_setImageWithURL(url)</code> a lot.</p>
  
  <p>However at some point I need to fetch an image manually from the imageCache, because I do not want to apply it to an UIImageView.</p>
  
  <p>This brings up 2 problems:</p>
  
  <ol>
  <li>I can access the image cache directly by creating one with <code>let imageCache = AutoPurgingImageCache()</code>. Is this <strong>the same cache</strong> as <code>.af_setImageWithURL()</code> uses (Singleton)? Or is this a new one? Which is worthless in my case, because I could not profit from the prefilled cache.</li>
  <li>Given this is the same cache: How can I fetch the correct image? I thought about <code>imageCache.imageForRequest(NSUrlRequest)</code>. Will this match on the images I downloaded before with <code>.af_setImageWithURL()</code> if the NSUrlRequest does use the same NSURL?</li>
  </ol>