swift: UIPageViewController动作

Question

我有UIPageViewController和这段代码可以翻转我的页面：

func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? { 
        let contentVC = viewController as! ContentViewController
        if contentVC.itemIndex > 0 {
            return getContentViewController(withIndex: contentVC.itemIndex - 1) 
        }

        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let contentVC = viewController as! ContentViewController
        if contentVC.itemIndex + 1 < images.count {
            return getContentViewController(withIndex: contentVC.itemIndex + 1)
        }

        return nil
    } 

但我想按下按钮翻页。我应该在按钮动作中打电话给viewControllerBefore和viewControllerAfter？还是我应该写另一段代码？该怎么做呢？

更新

override func viewDidLoad() {
        super.viewDidLoad()

        createPageViewController()
        setupPageControll()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func createPageViewController() {
        let pageController = self.storyboard?.instantiateViewController(withIdentifier: "PageViewController") as! UIPageViewController
        pageController.dataSource = self
        pageController.delegate = self

        if images.count > 0{
            let firstController = getContentViewController(withIndex: 0)!
            let contentControllers = [firstController]

            pageController.setViewControllers(contentControllers, direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)

        }

        pageViewController = pageController

        self.addChildViewController(pageViewController!)
        self.view.insertSubview(pageViewController!.view, at: 0)
        pageViewController!.didMove(toParentViewController: self)

    }

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

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

    func setupPageControll(){
        let apperance = UIPageControl.appearance()
        apperance.pageIndicatorTintColor = UIColor.gray
        apperance.currentPageIndicatorTintColor = UIColor.white
        apperance.backgroundColor = UIColor.clear
    }

    func currentControllerIndex() -> Int{
        let pageItemController = self.currentConroller()

        if let controller = pageItemController as? ContentViewController {
            return controller.itemIndex
        }
        return -1
    }

    func currentConroller() -> UIViewController?{
        if (self.pageViewController?.viewControllers?.count)! > 0{
            return self.pageViewController?.viewControllers![0]
        }

        return nil
    }

    func getContentViewController(withIndex index: Int) -> ContentViewController? {
        if index < images.count{
            let contentVC = self.storyboard?.instantiateViewController(withIdentifier: "ContentViewController") as! ContentViewController
            contentVC.itemIndex = index
            contentVC.imageName = images[index]

            return contentVC
        }

        return nil
    }

}

extension PageViewController: UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
        pendingIndex = (pendingViewControllers.first as! ContentViewController).itemIndex
    }

    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        if completed {
            let currentIndex = pendingIndex
            if let index = currentIndex {
                self.PageControl.currentPage = index
            }

        }
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let contentVC = viewController as! ContentViewController
        if contentVC.itemIndex > 0 {
            return getContentViewController(withIndex: contentVC.itemIndex - 1)
        }

        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let contentVC = viewController as! ContentViewController
        if contentVC.itemIndex + 1 < images.count {
            return getContentViewController(withIndex: contentVC.itemIndex + 1)
        }

        return nil
    }

新更新

新：

@IBAction func nextAction(_ sender: Any) {

        let pageController = self.storyboard?.instantiateViewController(withIdentifier: "PageViewController") as! UIPageViewController
        pageController.dataSource = self
        pageController.delegate = self

        let secondController = getContentViewController(withIndex: 1)!
        let contentControllers = [secondController]

        pageController.setViewControllers(contentControllers, direction: .forward, animated: true, completion: nil)

        pageViewController = pageController
    }

Answer 1

您需要使用此实例方法。

setViewControllers(_ viewControllers: UIViewController?，方向: UIPageViewController.NavigationDirection，动画: Bool，完成：((Bool) -> Void)？=0)

像这样

// self is of type UIPageViewController
self.setViewControllers([vc],direction:.forward,animated:true) { _ in
}

Answer 2

@IBAction func nextPageBtnPressed_TouchupInside(_ sender : UIButton ) {
    if let pageViewController = self.parent as? PageViewController {
        pageViewController.goToNextPage()
        pageViewController.changeCurrentPageIndicator(pageViewController: pageViewController)
    }
}


func goToNextPage(animated: Bool = true, completion: ((Bool) -> Void)? = nil) {
    if let currentViewController = viewControllers?[0] {
        if let nextPage = dataSource?.pageViewController(self, viewControllerAfter: currentViewController) {
            setViewControllers([nextPage], direction: .forward, animated: animated, completion: completion)
        }
    }


func changeCurrentPageIndicator(pageViewController : DTCPageViewController) {
    pageViewController.view.clipsToBounds = false
    pageViewController.view.sizeToFit()
    let pageContentViewController = pageViewController.viewControllers![0]
    currentIndex = orderViewController.index(of: pageContentViewController)!
    self.pageControl.currentPage = orderViewController.index(of: pageContentViewController)!
}

编写goToNextPage()和changeCurrentPageIndicator()