title: ios UIPageViewController swipe delay when jumping to page
body: <p>I have a UIPageViewController with several pages and when swiping through them, everything works well. The PageViewController automatically pre-loads the neighboring pages of the current one to ensure smooth scrolling (I have <code>UIPageViewControllerTransitionStyle.Scroll</code>)</p>
  
  <p>Additionally I can also jump to a specific page by entering a number. The problem is, when I jump to a certain page programmatically, the PageViewController doesn't seem to also pre-load neighboring pages, so when I start swiping from the page I just jumped to, there is a half-second delay, before the PageViewController loads the next ViewController so it can be displayed.</p>
  
  <p>I used this answer to jump to pages: <a href="https://stackoverflow.com/a/18602186/5461994">https://stackoverflow.com/a/18602186/5461994</a></p>
  
  <p>and transferred it to Swift:</p>
  
  <pre><code>weak var pvcw = pvc
  pvc.setViewControllers([page], direction: UIPageViewControllerNavigationDirection.Forward, animated: true) { finished in
     if let pvcs = pvcw {
          dispatch_async(dispatch_get_main_queue(), {
              pvcs.setViewControllers([page], direction: UIPageViewControllerNavigationDirection.Forward, animated: false, completion: nil)
          })
      }
  }
  </code></pre>
  
  <p>My question is: how can I get the UIPageViewController to pre-load the neighboring pages of a page I just jumped to, just like it automatically does during swiping?</p>
  
  <p>P.S.: I have the same problem on app launch. When I initialize my PageViewController and set the first visible page like this:</p>
  
  <pre><code>pvc.setViewControllers([firstPage], direction: UIPageViewControllerNavigationDirection.Forward, animated: false, completion: nil)
  </code></pre>
  
  <p>I also have this delay when swiping to the second page the first time.
  Any help is appreciated!</p>