gistfile1.m

    // TODO: Use weak self to avoid retaining self for a long time (during long downloads)
    SDWebImageManager *manager = [SDWebImageManager sharedManager];
    [manager downloadWithURL:imageURL
                     options:0
                    progress:nil
                   completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished)
     {
         if ( [self.imageURL isEqual:imageURL] &&
             image &&
             !error )
         {
             [self setAvatarImage:image];
         }
     }
     ];