在给定索引上启动 UIPageViewController

Question

我正在使用以下代码来初始化我的 UIPageViewController：

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

    if ((index == 0) || (index == NSNotFound)) {
        return nil;
    }

    index--;
    return [self viewControllerAtIndex:index];
}

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

    if (index == NSNotFound) {
        return nil;
    }

    index++;
    if (index == [self.roosterWeken count]) {
        return nil;
    }
    return [self viewControllerAtIndex:index];
}

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

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

    pageContentViewController.rooster = [self.roosterWeken objectAtIndex:index];
    pageContentViewController.pageIndex = index;

    return pageContentViewController;
}

- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController {
    return [self.roosterWeken count];
}

- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController {
    return 0;
}

在我的异步 AFNetworking 函数中，我在 Complete 上调用以下命令

 PageContentViewController *startingViewController = [self viewControllerAtIndex:0];
 NSArray *viewControllers = @[startingViewController];
 [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

一切正常，但我怎样才能让我的 UIPageViewController 例如在点 3 上启动？ （并且能够左右滚动，因为我们不在第一个点上）。

编辑

解决办法是：

PageContentViewController *startingViewController = [self viewControllerAtIndex:2];

Answer 1

要从点 3 开始，请将演示文稿索引设置为 2：

- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController {
    return 2;
}

并告诉 pageViewController 在初始化时显示该 viewController：

[self.pageViewController setViewControllers:[viewControllers[2]] direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];