title: How to load a webp image with SDWebImage?
body: <p>I'm using <a href="https://github.com/rs/SDWebImage" rel="nofollow">SDWebImage</a> to load images in my iOS app and I now want to use the webp format.</p>
  
  <p>Here's my first try :</p>
  
  <pre><code>NSURL *url = [NSURL URLWithString:@"http://www.gstatic.com/webp/gallery/2.webp"];
  
  [self.imageView setImageWithURL:url
                 placeholderImage:nil
                          options:SDWebImageProgressiveDownload
   completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
  
       if (error) {
  
           UIAlertView *av = [[UIAlertView alloc] initWithTitle:@"Error" message:error.localizedDescription delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
  
           [av show];
       }
   }];
  </code></pre>
  
  <p>It would work perfectly if the image was a jpeg (I tried) but with a webp it doesn't.
  The first time I call this code the error is :</p>
  
  <pre><code>Downloaded image has 0 pixels
  </code></pre>
  
  <p>Then the error turns to :</p>
  
  <pre><code>The operation couldn't be completed. (NSURLErrorDomain error -1100.)
  </code></pre>
  
  <p>What's wrong?</p>