title: UIScrollView header view?
body: <p>I have a controller, which has a UIView at the top with some buttons and labels. Underneath that I have a UIScrollView that contains content as well. I want the UIView on top to essentially work and appear as a header to this scroll view, similar to a UITableViewHeader. I'm using the scrollViewDidScroll delegate method with the contentOffset to try and get it to work, but I can't seem to get the right math. </p>
  
  <p>The idea is that as the scroll view scrolls up the "header" will scroll up with it relative to the content. It can even scroll off screen. Then as you scroll down it will stick to the top of the scroll view. Like I said, very similar functionality to a UITableViewHeader.</p>
  
  <p>Any help with figuring out the math for this would be greatly appreciated!</p>
  
  <p>Here is what I have so far:</p>
  
  <pre><code>    - (void)scrollViewDidScroll:(UIScrollView *)scrollView
  {
      CGRect updatedSegmentFrame = self.segmentedControlContainerView.bounds;
      CGRect updatedTableViewFrame = self.viewControllerThree.tableView.frame;
  
      CGFloat topEdge = -scrollView.contentOffset.y;
  
      if (topEdge &gt;= 0) {
          updatedSegmentFrame.origin.y = 0;
      }
      else {
          updatedSegmentFrame.origin.y = -scrollView.contentOffset.y;
      }
  
      self.viewControllerThree.tableView.frame = updatedTableViewFrame;
      self.segmentedControlContainerView.frame = updatedSegmentFrame;
  }
  </code></pre>
  
  <p>This code moves the external "header view" along with the UIScrollView with everything working as expected. The only thing missing is that as you scroll up the UIScrollView will need to get larger to offset the headerView going off the screen. </p>