title: SDWebImage and setting custom HTTP headers?
body: <p>I´ve just changed my code for caching images away from EGOImageCache to SDWebView. Unfortunately i don´t know how to set custom HTTP headers as i have to send authentification to be able to fetch images. It was easy done with EGOImageCache as i´ve extended the NSURLRequest at the appropriate place. But i don´t know how to do that with the SDWebView.framework. I see the headers and i´ve found methods in SDWebImageDownloader.h containing </p>
  
  <pre><code>    /**
   * Set a value for a HTTP header to be appended to each download HTTP request.
   *
   * @param value The value for the header field. Use `nil` value to remove the header.
   * @param field The name of the header field to set.
   */
  - (void)setValue:(NSString *)value forHTTPHeaderField:(NSString *)field;
  
  /**
   * Returns the value of the specified HTTP header field.
   *
   * @return The value associated with the header field field, or `nil` if there is no corresponding header field.
   */
  - (NSString *)valueForHTTPHeaderField:(NSString *)field;
  </code></pre>
  
  <p>It seems that the lib does support HTTP headers. But as i use UIImageView+WebCache.h i can´t see there an option for setting the headers. In my code i call</p>
  
  <pre><code>[self.imageView setImageWithURL:[NSURL URLWithString:themeImageURL] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
  </code></pre>
  
  <p>Can anybody tell me how to set HTTP headers?</p>