title: Is it possible to restrict scrolling within a UICollectionView to a subset of the items in the collection?
body: <p>Is it possible to restrict scrolling within a UICollectionView to a subset of the items in the collection?</p>
  
  <p>I have a UICollectionView that displays one item at a time. Each item takes the full width of the screen. The user can scroll horizontally between items.</p>
  
  <p>At times I want to be able to restrict the user to scrolling between a subset of items based on certain conditions. </p>
  
  <p>For example, view may contain items 1 through 20, but I only want the user to be able to scroll between items 7 and 9.</p>
  
  <p>I have tried changing the contentSize to just the width necessary to display the desired items, then changing the contentOffset, but this does not work.</p>