title: pageViewController setViewControllers crashes with "Invalid parameter not satisfying: [views count] == 3"
body: <p>I know that there are several other questions like this, but i couldn't find a solution for my problem.
  I use a pageViewController which displays different ViewControllers. Every time the pageViewController moves forward I check the input of the lastPage. If it's wrong the pageViewController should go back to that page by using the setViewController method. Without this method everything works fine but if I try to use it the app crashes with the following exception:  </p>
  
  <pre><code>19:48:25.596 Phook[23579:60b] *** Assertion failure in -[_UIQueuingScrollView _replaceViews:updatingContents:adjustContentInsets:animated:], /SourceCache/UIKit_Sim/UIKit-2935.137/_UIQueuingScrollView.m:383  
  2014-06-02 19:48:25.600 Phook[23579:60b] *** Terminating app due to uncaught   exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying:   [views count] == 3'
  </code></pre>
  
  <p>And here's my code:    </p>
  
  <pre><code>- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished
     previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
  {
      if (completed &amp;&amp; finished)
      {
  
          RegisterUserPageContent* lastPage = (RegisterUserPageContent*)previousViewControllers[ previousViewControllers.count-1];
          int lastIndex   = lastPage.pageIndex;
          int newIndex    = ((RegisterUserPageContent*)[self.pageViewController.viewControllers objectAtIndex:0]).pageIndex;
  
          if (newIndex &gt; lastIndex)
          {   // Moved Forward
              if(!lastPage.testInput)
              {
                  [self.pageViewController setViewControllers:@[ [self.storyboard instantiateViewControllerWithIdentifier:_pageStoryBoardIDs[0]] ]
                                           direction:UIPageViewControllerNavigationDirectionReverse
                                           animated:YES completion:nil];
  
  
              }
          }
          else
          {   // Moved Reverse
  
          }
      }
  }
  </code></pre>
  
  <p>As I already said. I searched a lot and implemented some solutions but nothing helped.
  Thanks.</p>