Question

我有两个标识符为“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;

}

此代码运行良好，但有问题！卷轴是无限的;在我的情况下，我需要脱掉无限卷轴。我怎么能这样做？

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，任何人都有更好的想法吗？

Answer 1

如果您只有两个页面，那么只需检查您何时收到页面请求，如果当前页面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类，您只需检查该类。否则你需要一些其他标准。

如果使用自定义类：

- (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

情况稍有变化。

 - (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？

2 个答案: