pagevc delegate, datasource

pagevc.swift

extension HomeViewController: UIPageViewControllerDataSource {

    func pageViewController(_ pageViewController: UIPageViewController,
                            viewControllerBefore viewController: UIViewController) -> UIViewController? {
        guard let index = mainViewControllers.firstIndex(of: viewController) else { return nil }
        let prevIndex = index - 1
        guard prevIndex >= 0, prevIndex < mainViewControllers.count else { return nil }
        return mainViewControllers[prevIndex]
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        guard let index = mainViewControllers.firstIndex(of: viewController) else { return nil }
        let nextIndex = index + 1
        guard nextIndex >= 0, nextIndex < mainViewControllers.count else { return nil }
        return mainViewControllers[nextIndex]
    }

    func presentationCount(for pageViewController: UIPageViewController) -> Int {
        return mainViewControllers.count
    }
}

extension HomeViewController: UIPageViewControllerDelegate {

    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        if completed {
            if let currentViewController = pageViewController.viewControllers?[0] {
                guard let index = mainViewControllers.firstIndex(of: currentViewController) else { return }
                pageControl.set(progress: index, animated: true)
            }
        }
    }
}


    func swipeRight() {
        guard let currentViewController = self.viewControllers?.first else {
            return
        }

        guard let nextViewController = dataSource?.pageViewController(self, viewControllerBefore: currentViewController) else {
            return
        }

        setViewControllers([nextViewController], direction: .reverse, animated: true) { completed in
            self.delegate?.pageViewController?(self,
                                               didFinishAnimating: true,
                                               previousViewControllers: [],
                                               transitionCompleted: completed)
        }
    }

    func swipeLeft() {
        guard let currentViewController = self.viewControllers?.first else {
            return
        }

        guard let nextViewController = dataSource?.pageViewController(self, viewControllerAfter: currentViewController) else {
            return
        }

        setViewControllers([nextViewController], direction: .forward, animated: true) { completed in
            self.delegate?.pageViewController?(self,
                                               didFinishAnimating: true,
                                               previousViewControllers: [],
                                               transitionCompleted: completed)
        }
    }