UIPageViewController transition from control on child UIViewController - ios

Question

I have a PageViewController, which has two UIViewControllers they are set up as follows:
ViewController.swift
override func viewDidLoad() {
super.viewDidLoad()
self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
self.pageViewController.dataSource = self
self.pageViewController.delegate = self
let startingViewController = self.viewControllerAtIndex(self.index)
let viewControllers: NSArray = [startingViewController]
self.pageViewController.setViewControllers(viewControllers as [AnyObject], direction: UIPageViewControllerNavigationDirection.Forward, animated: false, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height-10)
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
In one of the Child view controllers, I have a button which should transition to a specific index in the PageViewController:
#IBAction func createClick(sender: UIButton, forEvent event: UIEvent) {
let pageViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
let secondViewController = self.storyboard?.instantiateViewControllerWithIdentifier("NextViewController") as! UIViewController
let viewControllers: NSArray = [secondViewController]
pageViewController.self.setViewControllers(viewControllers as [AnyObject], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)
}
No errors, but the page does not transition. I'm thinking there is an issue with the delegation, but I'm not sure how to fix it.

Answer 1

The problem is that you aren't actually setting the viewControllers property on the UIPageViewController that your app is actually using - you are instantiating an entirely new UIPageViewController from the storyboard that has no relation to any of the controllers that are appearing on your screen.
One solution is to create a reference to your UIPageViewController in each of your child view controllers, like this:
weak var pageViewController: UIPageViewController?
In your dataSource, when you implement your "after" and "before" methods, i.e.: pageViewController:viewControllerBeforeViewController: and pageViewController:viewControllerAfterViewController: you will need to create the new child view controller, and then set the pageViewController property to a reference to the "parent" UIPageViewController.
Then, when your #IBAction method is invoked, you call the method on the pageViewController like this:
let secondViewController = self.storyboard?.instantiateViewControllerWithIdentifier("NextViewController") as! UIViewController
let viewControllers: NSArray = [secondViewController]
pageViewController?.setViewControllers(viewControllers as [AnyObject], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)
Something like that ought to work.