title: UIScrollView: paging horizontally, scrolling vertically?
body: <p>How can I force a <code>UIScrollView</code> in which paging and scrolling are on to only move vertically or horizontally at a given moment?</p>
  
  <p>My understanding is that the <code>directionalLockEnabled</code> property should achieve this, but a diagonal swipe still causes the view to scroll diagonally instead of restricting motion to a single axis.</p>
  
  <p>Edit: to be clearer, I'd like to allow the user to scroll horizontally OR vertically, but not both simultaneously.</p>