no page control displayed even after implementing delegate methods

问题

Page view controller not display after adding delegate and datasource. how to implement pageViewController Datasource and delegate

import UIKit

DataSource

class PageViewController: UIPageViewController ,UIPageViewControllerDataSource,UIPageViewControllerDelegate
{
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let vc = storyboard?.instantiateViewController(withIdentifier: "vc") as! ViewController

        return vc

    }
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let vc = storyboard?.instantiateViewController(withIdentifier: "vc") as! ViewController

        return vc
    }
    func presentationCount(for pageViewController: UIPageViewController) -> Int {
        return 3
    }
    override func index(ofAccessibilityElement element: Any) -> Int {
        return 0
    }

setting a delegate and datasource in ViewDidLoad

    override func viewDidLoad() {
        super.viewDidLoad()
         dataSource=self
        delegate = self
        let vc = storyboard?.instantiateViewController(withIdentifier: "vc") as! ViewController
       self.setViewControllers([vc], direction: .forward, animated: true, completion: nil)

     }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

回答1:

Replacing

 override func index(ofAccessibilityElement element: Any) -> Int {
        return 0
    }

with

func presentationIndex(for pageViewController: UIPageViewController) -> Int {
        return 0
    }

did the work.

I was calling wrong method

来源：https://stackoverflow.com/questions/42196932/no-page-control-displayed-even-after-implementing-delegate-methods