具有多个视图的UIPageViewController

我需要一个动态的UIPageViewController，页面数取决于我数组中项目的数量。

我对此有两种看法。一个用于第一页，另一个用于其他页。它将始终超过2页（我的阵列上有两个项目）。

我正在尝试使用固定值进行测试。但是分页是不正确的。索引不正确。

第一个问题，presentationCountForPageViewController [_vc count]返回nil；

第二个问题，分页不正确。我到达最后一页，第一个视图消失了，因此，如果我返回，则总是转到第二个视图...

请帮忙！

    - (void)viewDidLoad {
        [super viewDidLoad];

        FirstViewController *agenda = (FirstViewController*)[self viewControllerAtIndex:0];
        [_vc addObject:@"FirstViewController"];
        [_vc addObject:@"SecondViewController"];


        self.pageViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"PageViewController"];
        self.pageViewController.dataSource = self;


        NSArray *viewControllers = [NSArray arrayWithObject:agenda];

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


        [self addChildViewController:_pageViewController];
        [self.view addSubview:_pageViewController.view];
        [self.pageViewController didMoveToParentViewController:self];

        UIPageControl *pageControlAppearance = [UIPageControl appearanceWhenContainedIn:[UIPageViewController class], nil];
        pageControlAppearance.pageIndicatorTintColor = [UIColor lightGrayColor];
        pageControlAppearance.currentPageIndicatorTintColor = [UIColor darkGrayColor];


    }




- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{

    NSUInteger index = [_vc indexOfObject:viewController];

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

    index--;

    //notice here I call my instantiation method again essentially duplicating work I have already done!
    return [self viewControllerAtIndex:index];
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    NSUInteger index = [_vc indexOfObject:viewController];

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

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


#pragma mark - Page View Controller Data Source

- (UIViewController *)viewControllerAtIndex:(NSUInteger)index
{

    if (index == 0){
        FirstViewController *firstController = [self.storyboard instantiateViewControllerWithIdentifier:@"FirstViewController"];

        return firstController;
    }
    else{
        SecondViewController *secondController = [self.storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
        return secondController;
    }

}

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

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