PageViewController 显示页面索引不正确？

Question

我已按照本教程创建 PageViewController http://www.appcoda.com/uipageviewcontroller-storyboard-tutorial/ 问题是我错误地获取了页面，其余的一切都很完美

如果页面索引是最后一个索引，我需要做一些事情，然后我更改按钮标签。

- (PageContentViewController *)viewControllerAtIndex:(NSUInteger)index
{
    if (([self.pageImages count] == 0) || (index >= [self.pageImages count])) {
        return nil;
    }

    // Create a new view controller and pass suitable data.
    PageContentViewController *pageContentViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"PageContentViewController"];
    pageContentViewController.imageFile = self.pageImages[index];
    pageContentViewController.titleText = self.pageTitles[index];

    pageContentViewController.pageIndex = index;

    NSLog(@"INDEX : %lu", (unsigned long)index);

    return pageContentViewController;
}

- (void)pageViewController:(UIPageViewController *)pageViewCntr didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
    NSInteger currentIndex = ((UIViewController *)self.pageViewController.viewControllers.firstObject).view.tag;
    if (completed) pageControl.currentPage = currentIndex;
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    NSInteger index = ((PageContentViewController *)viewController).pageIndex;

    if (index == NSNotFound || !index) return nil;
    NSLog(@"INDEX : %lu", (unsigned long)index);
    return [self viewControllerAtIndex:index-1];
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    NSInteger index = ((PageContentViewController *)viewController).pageIndex;

    if (index == NSNotFound || index == pageCount-1) return nil;
    NSLog(@"INDEX : %lu", (unsigned long)index);
    return [self viewControllerAtIndex:index+1];
}



- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController{

    return [self.pageImages count];

}

- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController{

    return 0;
}

我尝试了很多方法，但无法解决问题。

帮助我找到页面的当前索引。 页面索引当前未显示，当我滑动一次时，它一次返回 0,1 个索引，下一次滑动它显示我 2，下一次滑动它不返回任何索引

Answer 1

我已经实现了相同的代码，在调试之后，我知道PageViewControllerDataSource 方法被调用了两次。因此，您可以使用willTransitionToViewControllers 方法而不是viewControllerBeforeViewController 和viewControllerAfterViewController 方法来获取正确的索引。

请参考以下答案，

PageViewController delegate functions called twice