How to jump back to a first index of a page in UIPageviewController

Question

I currently have a button that currently displays a UIPageViewController as an overlay on the homescreen. The user can always click on it and it would still display this ViewControllers embedded in a UIPageViewController. However at the moment, when the user clicks on the button to display the overlay and closes it and opens it again. The last page index / state of the last page is saved and displayed again. What i would like to do is to always display the first ViewController in the UIPageviewController. I have tried different ways but haven't had any luck.

Here is the screen capture that shows how the current mechanism works

https://gph.is/g/Z2QlyDa

HomeHelpViewController that contains the UIPageViewController

class HomeHelpViewController: UIPageViewController, UIPageViewControllerDataSource {

    var helpPages: [UIViewController] = []
    var currentIndex: Int = 0

    override func viewDidLoad() {
        super.viewDidLoad()
        let helpStoryboard = UIStoryboard(name: "HomeHelp", bundle: nil)
        for scanIdentifier in ["homeHelpVC1","homeHelpVC2","homeHelpVC3","homeHelpVC4"] {
            let scanVC = helpStoryboard.instantiateViewController(withIdentifier: scanIdentifier)
            self.helpPages.append(scanVC)
        }
        self.dataSource = self
        self.setViewControllers([self.helpPages.first!], direction: .forward, animated: true)
    }

    //MARK:- UIPageViewControllerDataSource

    func pageViewController(_ pPageViewController: UIPageViewController, viewControllerBefore pViewController: UIViewController) -> UIViewController? {
        self.currentIndex = self.helpPages.firstIndex(of: pViewController)!
        if self.currentIndex > 0 {
            return self.helpPages[self.currentIndex - 1]
        }
        return nil
    }

    func pageViewController(_ pPageViewController: UIPageViewController, viewControllerAfter pViewController: UIViewController) -> UIViewController? {
        self.currentIndex = self.helpPages.firstIndex(of: pViewController)!
        if self.currentIndex < (self.helpPages.count - 1) {
            return self.helpPages[self.currentIndex + 1]
        }
        return nil
    }

    func presentationCount(for pPageViewController: UIPageViewController) -> Int {
        return self.helpPages.count
    }

    func presentationIndex(for pPageViewController: UIPageViewController) -> Int {
        return self.currentIndex
    }
}

HomePageViewController that has the button display the UIPageViewController as an overlay

class HomePageViewController: UIViewController {

     @IBOutlet weak var helpOverlay: BaseOverlayView!

     @IBAction func helpButton(_ pSender: Any) {
            self.helpButton.setImage(AppDelegate.helpButtonImage(tutorial: true), for: .normal)
            self.helpOverlay.showOnView(self.view)
        }

     @IBAction func closeHelp(_ pSender: UIButton) {
            self.helpOverlay.removeFromView()
            self.helpButton.setImage(AppDelegate.helpButtonImage(tutorial: false), for: .normal)
        }
}

Answer 1

declare a variable to access your HomeHelpViewController inside your HomePageViewController

    class HomePageViewController: UIViewController {

         weak var homePageController : HomeHelpViewController?

         @IBOutlet weak var helpOverlay: BaseOverlayView!

         @IBAction func helpButton(_ pSender: Any) {
    if let homePageController = homePageController {
    homePageController.setViewControllers([homePageController.helpPages.first!], direction: .forward, animated: true)
}
                self.helpButton.setImage(AppDelegate.helpButtonImage(tutorial: true), for: .normal)
                self.helpOverlay.showOnView(self.view)
            }

         @IBAction func closeHelp(_ pSender: UIButton) {
                self.helpOverlay.removeFromView()
                self.helpButton.setImage(AppDelegate.helpButtonImage(tutorial: false), for: .normal)
            }
    }

inside this loop assign your HomeHelpViewController

for scanIdentifier in ["homeHelpVC1","homeHelpVC2","homeHelpVC3","homeHelpVC4"] {
                let scanVC = helpStoryboard.instantiateViewController(withIdentifier: scanIdentifier) as? HomePageViewController
    scanVc?.homePageController = self
                self.helpPages.append(scanVC)
            }