如何删除 UIPageViewController 上的无限滚动？

Question

我有两个带有标识符 "one" 和 "two" 的故事板，我有一个 UIPageViewController 及其子类。在子类中，我有以下代码：

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.dataSource = self;
    self.delegate = self;
    counter = 0;

    [self setViewControllers:@[[self.storyboard instantiateViewControllerWithIdentifier:@"one"]] direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
}

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

    if ([viewController isKindOfClass:[ViewController class]]){
    return [self.storyboard instantiateViewControllerWithIdentifier:@"one"];
    }

    return nil;


}


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

    if ([viewController isKindOfClass:[secondViewController class]]){
    return [self.storyboard instantiateViewControllerWithIdentifier:@"two"];
    }

    return nil;

}

这段代码工作得很好，但是有一个问题！滚动是无限的；就我而言，我需要取下无限卷轴。我该怎么做？

首先是创建一个计数器并在我的方法中进行检查：

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

    if (counter < 1) {
        NSLog(@"Don't get back");
        return nil;
    }

    ......

}


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

    if (counter >= 1) {
        NSLog(@"Don't go anymore");
        return nil;
    }

    ....
}

第二件事是尝试使用counter++和counter--。这对我来说是个大难题，有人有更好的主意吗？

Answer 1

如果您只有两个页面，那么在收到页面请求时只需检查当前页面是否已经不是您要提供的页面。为此，您需要一种方法来识别它。

如果每个页面都有不同的 class，您只需检查 class。否则你需要一些其他标准。

如果使用自定义 classes:

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    if ([viewController isKindOfClass:[ClassOfSecondViewController class]])
    {
        return [self.storyboard instantiateViewControllerWithIdentifier:@"one"];
    }

    return nil;
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    if ([viewController isKindOfClass:[ClassOfFirstViewController class]])
    {
        return [self.storyboard instantiateViewControllerWithIdentifier:@"two"];
    }
    return nil;
}

Answer 2

只是条件稍有变化。

 - (nullable UIViewController *)pageViewController:(nonnull UIPageViewController *)pageViewController viewControllerBeforeViewController:(nonnull UIViewController *)viewController {
        NSUInteger currentIndex = [pages indexOfObject:viewController];
        NSUInteger previousIndex = ((currentIndex - 1) % pages.count);
        if (viewController == yourFirstViewController)
            return nil;
        return pages[previousIndex];
    }

    - (nullable UIViewController *)pageViewController:(nonnull UIPageViewController *)pageViewController viewControllerAfterViewController:(nonnull UIViewController *)viewController {
        NSUInteger currentIndex = [pages indexOfObject:viewController];
        NSUInteger nextIndex = ((currentIndex + 1) % pages.count);
        if (viewController == yourLastViewController)
            return nil;
        return pages[nextIndex];
    }

如何删除 UIPageViewController 上的无限滚动？

How to remove infinite scroll on UIPageViewController?

ios

objective-c

uipageviewcontroller