title: Refresh UIPageViewController - reorder pages and add new pages
body: <p>I have a <code>UIPageViewController</code> which I am providing page data for using an implementation of <code>UIPageControllerDelegate</code> and <code>UIPageControllerDataSource</code>.</p>
  
  <p>It's all working fine, but I want to be able to add items to the page data and reorder the page data.</p>
  
  <p>If a user has already got to the last of the pages, and then I add an item, they can't get to the next page because <code>viewControllerAfterViewController:</code> has already been called. If they scroll back one and then forward two they can get to the new page fine, so the data is setup correctly. How can I tell the <code>UIPageViewController</code> to refresh its store of what comes next?</p>
  
  <p>Similarly I would like to reorder the collection that is backing the page view. But if I do this I'll get the same problem - the page view will think the next page is still what it was last time the current page was loaded.</p>
  
  <p>I guess I'm looking for something similar to <code>reloadData:</code> on <code>UITableView</code>.</p>