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This function is never printing:

func pageViewController(_ pageViewController: UIPageViewController,

                        didFinishAnimating finished: Bool,

                        previousViewControllers: [UIViewController],

                        transitionCompleted completed: Bool){

    if completed||finished{



        print("completed or finished")

    }

}

why?

entire code:

class AdsPageController: UIPageViewController, 

UIPageViewControllerDataSource

{

var AdsContent: AdsController? = nil

static var adsPageController:AdsPageController?



override func viewDidLoad() {

    super.viewDidLoad()

    self.dataSource = self

    AdsPageController.adsPageController = self

}



override func viewWillAppear(_ animated: Bool) {

    self.setViewControllers([getViewControllerAtIndex(pageIndex: MyUtils.loadAdIndex())] as [UIViewController], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)

}



// MARK: UIPageViewControllerDataSource Methods

func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController?

{

    self.AdsContent = viewController as? AdsController

    var index = AdsContent!.pageIndex

    if ((index == 0) || (index == NSNotFound))

    {

        index = 10

    }

    index-=1

    return getViewControllerAtIndex(pageIndex: index)

}



func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController?

{

    self.AdsContent = viewController as? AdsController

    var index = AdsContent!.pageIndex

    if ((index == 9) || index == NSNotFound)

    {

        index = -1

    }

    index+=1

    return getViewControllerAtIndex(pageIndex: index)

}



func pageViewController(_ pageViewController: UIPageViewController,

                        didFinishAnimating finished: Bool,

                        previousViewControllers: [UIViewController],

                        transitionCompleted completed: Bool){

    if completed||finished{

        print("completed or finished")

    }

}



func getViewControllerAtIndex(pageIndex: NSInteger) -> AdsController{

    let AdsContent: AdsController? = self.storyboard?.instantiateViewController(withIdentifier: "AdViewP") as? AdsController

    AdsContent?.pageIndex = pageIndex

    return AdsContent!

}

}

I want to know when a page transition has completed, I've implemented the didFinishAnimating method from UIPageViewController, but it's seems not working properly.

That's because:

pageViewController(_:didFinishAnimating:previousViewControllers:transitionCompleted:)

method relates to UIPageViewControllerDelegate

which means that you should implement -in addition to self.dataSource = self-:

override func viewDidLoad() {

    super.viewDidLoad()

    self.dataSource = self

    // here you conform to the delegate (note that you could implement it without mentioning 'self.'):

    delegate = self

    AdsPageController.adsPageController = self

}

And it should work as expected. Also, make sure to let the class to conform to UIPageViewControllerDelegate:

class AdsPageController: UIPageViewController,

UIPageViewControllerDataSource, UIPageViewControllerDelegate

Furthermore, you could check this answer to be more familiar with Delegation.