title: UIScrollView with fixed contents inside
body: <p>my question is:
  In my app I want realize somethings like this using <code>UIScrollView</code></p>
  
  <p><img src="https://i.stack.imgur.com/55RAS.jpg" alt="enter image description here"></p>
  
  <p>A <code>UIScrollView</code> whit all his contents inside. But when I reached the top of the screen (or maybe the bottom of the screen) I want to anchor some contents like in the AppStore (iOS 6).</p>
  
  <p><img src="https://i.stack.imgur.com/9Vugt.jpg" alt="enter image description here"></p>
  
  <p>In this case the "Detail", "Review" and "Related" buttons stop scrolling and remains fixed at the top.</p>
  
  <p>Anyone have any idea how to do?</p>