swift - UIPageController - 如果取消滑动则检测当前页面 (SWIFT 3.*)

Question

我目前有一个 UIPageController，它可以在滚动时正确检测到上一个或下一个 pageIndex

我需要解决的问题是...

例子:-用户向左或向右滚动，但随后决定在滑动期间取消……因此保留在当前页面上。

pageIndex 更改为待定页面(下一页)而不是实际的当前页面..

我的代码目前实现了上面的语句:--

func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {

    if let itemController = pendingViewControllers[0] as? PageContentViewController {

        nextIndex = itemController.pageIndex

        print("Page index = \(nextIndex)")
    }
}

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        currentIndex = nextIndex
        print("Current Page = \(currentIndex)")
    }


func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {



    let itemController = viewController as! PageContentViewController

    if itemController.pageIndex < numberOfPages {
        return getItemController(itemController.pageIndex+1)
    }

    return nil

}



func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {

    let itemController = viewController as! PageContentViewController

    if itemController.pageIndex > 0 {

        return getItemController(itemController.pageIndex-1)
    }

    return nil
}

func getItemController(_ itemIndex: Int) -> PageContentViewController? {

    if itemIndex < numberOfPages {
        let pageItemController = self.storyboard!.instantiateViewController(withIdentifier: "Page1") as! PageContentViewController
        pageItemController.pageIndex = itemIndex

        return pageItemController
    }

    return nil
}

我想在页面显示之前获取页码，以便我可以显示特定对象等。

viewControllerAfter 和 viewControllerBefore 似乎不是每次都被调用因此我不能依赖这个委托(delegate)方法

Answer 1

我不知道我是怎么错过的，但在 didFinishAnimating 方法中，它们是一个完成 block

因此下面的代码解决了我的问题

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {

    if completed
    {
        currentIndex = nextIndex

    }

    print("Current Page = \(currentIndex)")
}