如何跳回 UIPageviewController 中页面的第一个索引答案

【问题标题】：How to jump back to a first index of a page in UIPageviewController如何跳回 UIPageviewController 中页面的第一个索引
【发布时间】：2019-03-06 09:11:32
【问题描述】：

我目前有一个button，它当前在主屏幕上显示UIPageViewController 作为叠加层。用户可以随时点击它，它仍然会显示这个嵌入在UIPageViewController 中的ViewControllers。但是目前，当用户单击按钮以显示覆盖并关闭它并再次打开它时。最后一页的索引/最后一页的状态被保存并再次显示。我想做的是始终在UIPageviewController 中显示第一个ViewController。我尝试了不同的方法，但没有任何运气。

这是显示当前机制如何工作的屏幕截图

https://gph.is/g/Z2QlyDa

HomeHelpViewController 包含 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
    }
}

具有按钮的 HomePageViewController 将 UIPageViewController 显示为叠加层

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)
        }
}

【问题讨论】：

标签： ios swift uipageviewcontroller uipagecontrol

【解决方案1】：

声明一个变量来访问 HomePageViewController 中的 HomeHelpViewController

    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)
            }
    }

在这个循环中分配你的 HomeHelpViewController

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

【讨论】：

如何在helpbutton action 中访问self.setViewControllers([self.helpPages.first!], direction: .forward, animated: true) 。这是另一个viewController

【解决方案2】：

这可能是因为 UIPageViewController 没有正确关闭。

func dismiss(animated flag: Bool, completion: (() -> Void)? = nil)

您可以参考这里的文档：https://developer.apple.com/documentation/uikit/uiviewcontroller/1621505-dismiss

这有效地解除了 UIPageViewController 的分配，因此一旦按下按钮，它将在第一页重新初始化。

【讨论】：