Why is the page not changing in my UIPageViewController?

Question

I have a UIPageViewController set up containing 5 view controllers that I created in storyboard. The pages change just fine with a swipe gesture, but I want the page to change after the user taps a button within one of the view controllers. Here's my code:

//  PageVC.swift

import Foundation
import UIKit

class PageVC: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    lazy var VCArr: [UIViewController] = {
        return [self.VCInstance(name: "OB1"),
                self.VCInstance(name: "OB2"),
                self.VCInstance(name: "OB3"),
                self.VCInstance(name: "OB4"),
                self.VCInstance(name: "OB5"),
                self.VCInstance(name: "OB6")]
    }()

    private func VCInstance(name: String) -> UIViewController {
        return UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: name)

    }

    override public func viewDidLoad() {
        super.viewDidLoad()
        self.dataSource = self
        self.delegate = self
        if let OB1 = VCArr.first {
            setViewControllers([OB1], direction: .forward, animated: true, completion: nil)
        }
    }

    public func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController?{
        guard let viewControllerIndex = VCArr.index(of: viewController) else {
            return nil
        }

        let previousIndex = viewControllerIndex - 1

        guard previousIndex >= 0 else {
            return VCArr.last
        }

        guard VCArr.count > previousIndex else {
            return nil
        }

        return VCArr[previousIndex]
    }

    public func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController?{
        guard let viewControllerIndex = VCArr.index(of: viewController) else {
            return nil
        }

        let nextIndex = viewControllerIndex + 1

        guard nextIndex < VCArr.count else {
            return VCArr.first
        }

        guard VCArr.count > nextIndex else {
            return nil
        }

        return VCArr[nextIndex]
    }

    public func presentationCount(for pageViewController: UIPageViewController) -> Int{

        return VCArr.count

        }

    public func presentationIndex(for pageViewController: UIPageViewController) -> Int{

        guard let OB1 = viewControllers?.first,
            let OB1Index = VCArr.index(of: OB1) else {
                return 0

        }

        return OB1Index
    }

    public func nextPageWithIndex(index: Int)
    {
        let nextVC = VCArr[index]
        setViewControllers([nextVC], direction: .forward, animated: true, completion: nil)

    }


}

I call the nextPageWithIndex method here in an IBAction in one of my view controllers:

//  OB1.swift

import UIKit

class OB1: UIViewController {
    @IBOutlet var getStartedColorChange: UIButton!


    override func viewDidLoad() {
        super.viewDidLoad()



    }

    @IBAction func getStartedBtn(_ sender: Any) {

        let getStarted = PageVC()
        getStarted.nextPageWithIndex(index: 2)

    }

}

The button works, as I am able to print from it, but the page isn't changing. What do I need to change in order to change pages using the button?

Answer 1

The problem is the new instance of PageVC() in your code:

let getStarted = PageVC()

You must get the reference to parent controller that already created!

  @IBAction func getStartedBtn(_ sender: Any) {
        let getStarted = self.parent as! PageVC
        getStarted.nextPageWithIndex(index: 2)
    }