title: Tweetbot banner image pull down to zoom image
body: <p>Tweetbot and Kickstarter for iOS uses a cool feature on user profiles that have a banner image. If you pull down on the <code>tableView</code> the image zooms.</p>
  
  <p>I have it partially working using the following, it changes the height of the image, but strangely, not the width:</p>
  
  <pre><code>- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  
      UIImageView *imageView = (UIImageView *)self.tableView.tableHeaderView;
      CGFloat y = -scrollView.contentOffset.y;
      imageView.frame = CGRectMake(0, scrollView.contentOffset.y, self.cachedImageViewSize.size.width+y, self.cachedImageViewSize.size.height+y);
      NSLog(@"%@", NSStringFromCGRect(imageView.frame));
  
  }
  </code></pre>
  
  <p>Does anyone know how to recreate this effect?</p>