ios - 在 UIPageViewController 中检查后退/前进滚动时的错误

Question

我正在尝试将适当的图像从数组加载到我的 UIPageViewController 的 View 中。 我循环浏览 3 个 View 以防止崩溃。

我会跟踪我是向前滚动还是向后滚动，但有时当我快速前后翻转时，我遇到了一个翻转方向的错误，然后我得到了重复几次滚动的相同 View 。

这是滚动完成时更新局部变量索引的函数

func pageViewController(pvc: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
     if completed {
                let thisPage = pvc.viewControllers!.last as! PageContentViewController
                let currentIndex = thisPage.pageIndex

                let lastIndex = lastPage.pageIndex
                  if(currentIndex > urlIndex){   
                    urlIndex += 1
                }else if(currentIndex < urlIndex) {
                    urlIndex -= 1
                }else{

                }
            }
        }

下面是我的 UIPageViewController 代码的其余部分:

 override func viewDidLoad() {
        super.viewDidLoad()
        dataSource = self
        delegate = self
}

   private(set) lazy var orderedViewControllers: [PageContentViewController] = {
    return [self.newPageContentViewController(),
            self.newPageContentViewController(),
            self.newPageContentViewController()
    ]
}()

private func newPageContentViewController() -> PageContentViewController {
    return UIStoryboard(name: "Main", bundle: nil) .
        instantiateViewControllerWithIdentifier("PageContentViewController") as! PageContentViewController
}

private func getNextViewController() -> PageContentViewController{

    let scrollView = orderedViewControllers.removeAtIndex(0)
    orderedViewControllers.append(scrollView)
    return scrollView
}

private func getPreviousViewController() -> PageContentViewController{

    let scrollView = orderedViewControllers.removeLast()
    orderedViewControllers.insert(scrollView, atIndex: 0)
    return scrollView
}

  func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController?
{
    guard urlIndex > 0 else {
        return nil
    }

    let previousUrlIndex = urlIndex - 1


    return getViewControllerAtIndex(previousUrlIndex, next: false)
}

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

    let nextUrlIndex = urlIndex + 1
    guard arrayRouteName.count > nextUrlIndex else{
        return nil
    }


    return getViewControllerAtIndex(nextUrlIndex, next: true)
}

func getViewControllerAtIndex(index: NSInteger, next: Bool) -> PageContentViewController
{

    // Create a new view controller and pass suitable data.
    var pageContentViewController:PageContentViewController
    if(next){
        pageContentViewController = getNextViewController()
    }else{
        pageContentViewController = getPreviousViewController()
    }
  pageContentViewController.localImage = arrayLocalImage[index]


    pageContentViewController.pageIndex = index
    pageContentViewController.view.clipsToBounds = true
    return pageContentViewController
}

Answer 1

我已经设法解决了这个问题。我已经从 UIPageControllerDelegate 中删除了 pageViewController 函数，只是简单地更改了我的数据源中的 pageViewController 函数，以便从 viewController 中获取索引，就像这样

 func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController?
{ 
let index = ((viewController as! UIPageContentViewController).pageIndex) - 1
guard index < 0 {
    return nil
}

return getViewControllerAtIndex(index, pageContentViewController: getPreviousViewController() ) 
}

它的行为就像它应该的那样。