我正在尝试呈现一个带有 3 个 ContentViewController 的 PageViewController，用户可以在其中从一个页面移动到下一个页面，还可以使用计时器自动滚动到下一个页面。

第一个问题:如何让页面 View Controller 正确更新页面底部的点。

我已经实现了三页 PageViewController 并且有一个基于计时器的自动化。计时器调用:

@objc func animation() {
    if counter < 2  {counter += 1}
    else {counter = 0}        
    self.pageViewController.setViewControllers([self.pageTutorialAtIndex(counter)], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)
}

调用 setViewControllers 会改变 View 。 但是，它不会更新页面底部的 PageViewController 点。需要做什么来解决这个问题？

很明显，这个类级别的计数器没有得到当前显示的 ViewContoller，这引出了我的第二个问题。

第二个问题: 如何正确地实现从显示的页面获取当前索引？我试过:

let current = self.pageTutorialAtIndex(0) as SplashContentViewController
var counter : Int = current.pageIndex!

认为这是读取当前页，但似乎只读取第 0 页。

类和 viewDidLoad 是:

class SplashViewController: UIViewController, UIPageViewControllerDataSource {

    var pageImages:NSArray!
    var pageTitles:[String]!
    var pageTexts:[String]!
    var pageViewController:UIPageViewController!
    var waitTimer : Timer!
    var counter : Int = 0

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        pageImages = NSArray(objects:"sp_image1","sp_image2","sp_image3")
        pageTitles = [NSLocalizedString("sp_title1",comment: ""), NSLocalizedString("sp_title2", comment: ""), NSLocalizedString("sp_title3", comment: "")]
        pageTexts = [NSLocalizedString("sp_detail1",comment: ""), NSLocalizedString("sp_detail2", comment: ""), NSLocalizedString("sp_detail3", comment: "")]

        self.pageViewController = self.storyboard?.instantiateViewController(withIdentifier: "SplashPageViewController") as! UIPageViewController
        self.pageViewController.dataSource = self
        let initialContenViewController = self.pageTutorialAtIndex(0) as SplashContentViewController
        self.pageViewController.setViewControllers([initialContenViewController], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)
        self.addChildViewController(self.pageViewController)
        self.view.addSubview(self.pageViewController.view)
        self.pageViewController.didMove(toParentViewController: self)
    }

通过实现委托(delegate)方法:

func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController?
    {
        let viewController = viewController as! SplashContentViewController
        var index = viewController.pageIndex as Int
        if(index == 0 || index == NSNotFound){return nil}
        index -= 1
        return self.pageTutorialAtIndex(index)
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController?
    {
        let viewController = viewController as! SplashContentViewController
        var index = viewController.pageIndex as Int
        if((index == NSNotFound)){return nil}
        index += 1
        if(index == pageImages.count){return nil}
        return self.pageTutorialAtIndex(index)
    }

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

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

最佳答案

我似乎找到了一个可能的答案:

第一个问题:如何让页面 View Controller 正确更新页面底部的点。而不是返回 0，返回当前计数器提供了权利。

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

第二个问题:如何实现获取当前索引？在我的解决方案中，计数器变量标识当前页面。它无法从显示的页面正确获取索引，但可以正常工作。

全局计数器变量的实现是:

func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController?
{
    let viewController = viewController as! SplashContentViewController
    let index = viewController.pageIndex as Int

    if(index == NSNotFound){
        return nil
    }
    if(index > 0){
        counter = index - 1
        return self.pageTutorialAtIndex(counter)
    } else {
        counter = 0
        return nil
    }
}

func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController?
{
    let viewController = viewController as! SplashContentViewController
    let index = viewController.pageIndex as Int
    if((index == NSNotFound)){
        return nil
    }
    if (index < pageImages.count - 1) {
        counter = index + 1
        return self.pageTutorialAtIndex(counter)
    } else {
        counter = pageImages.count - 1
        return nil
    }
}

关于ios - 更新 ViewController 不更新 PageViewController 点，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49572561/