title: Change page in PageViewController from a page inside the controller?
body: <p>I have a <code>UIPageViewController</code> that has 3 pages. How can I switch to a page that is within the <code>UIPageViewController</code> on a button tap? (Each of the pages are a separate <code>UIViewController</code> that I made in the storyboard).</p>
  
  <p>I've tried a lot of code but I keep getting errors as I made my <code>UIPageViewController</code> inside my storyboard and I set it up like this:</p>
  
  <p><code>PageViewController.m</code></p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
  
      self.dataSource = self;
      self.navigationController.navigationBarHidden = NO;
  
      [self setViewControllers:@[[self.storyboard instantiateViewControllerWithIdentifier:@"Main"]] 
                     direction:UIPageViewControllerNavigationDirectionForward 
                      animated:YES
                    completion:nil];
  }
  
  - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
  {
      if ([viewController isKindOfClass:[NavView2ViewController class]])
         return nil;
  
      return [self.storyboard instantiateViewControllerWithIdentifier:@"two"];
  }
  
  - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
  {
      if ([viewController isKindOfClass:[NavViewController class]])
          return nil;
  
      return [self.storyboard instantiateViewControllerWithIdentifier:@"one"];
  }
  </code></pre>