iOS中的UIPageViewController自动滚动

Question

我正在制作一个应用程序，其中 PageViewController 应该在某个时间间隔内滚动。目前我已经完成了手动滚动。用户可以滚动任何图像，它会工作。但坚持通过用户触摸实现自动滚动。下面是我的代码。请帮我解决这个问题。

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    _pageTitles = @[@"", @"", @"", @""];
    _pageImages = @[@"page1.png", @"page2.png", @"page3.png", @"page4.png"];

    // Create page view controller
    self.pageViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"PageViewController"];
    self.pageViewController.dataSource = self;

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

    // Change the size of page view controller
    self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - 50);

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

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

    return pageContentViewController;
}

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:YES];

    self.navigationController.navigationBar.hidden = YES;
}

#pragma mark - Page View Controller Data Source

- (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.pageTitles count]) {
        return nil;
    }
    return [self viewControllerAtIndex:index];
}

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

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

Answer 1

@Daniel 您的链接已损坏，您的“答案”几乎无法解释您对问题的解决方案。对于那些有兴趣阅读UIPageViewController Class 文档的人。

这里要注意的方法是：

- (void)setViewControllers:(NSArray *)viewControllers
                 direction:(UIPageViewControllerNavigationDirection)direction
                  animated:(BOOL)animated
                completion:(void (^)(BOOL finished))completion

UIPageViewController 期望您根据值告诉它要传递什么数据以及使用什么控制器。在这里，我告诉我的 UIPageController 子类是委托和数据源。配置委托方法和 viewControllerAtIndex 数据源方法后，我添加了一个自定义间隔，它调用我的 loadNextController 方法。在那种方法中，我正在检查“下一个”控制器是否为零。如果它不是 nil，我将“下一个”控制器作为 @[starting controller] 传递回对 setViewControllers 的第二次调用。如果它是 nil，我只需将索引值重置为零并使用我的“下一个”控制器作为@[起始控制器]调用 setViewControllers。此自定义子类用于自动分页到下一个或第一个控制器。好处是用户交互仍然由 UIPageViewController 类处理。

注意：需要对 setViewControllers 进行初始调用，因为您的 UIPageViewContrller 将不知道是否可以先加载任何 viewController。我对 setViewControllers 的第二次调用只不过是跳到下一个或第一个 viewController。

- (void)viewDidLoad {
    [super viewDidLoad];
    self.index = 0;
    self.delegate = self;
    self.dataSource = self;

    /*! setup an interval */
    [NSTimer scheduledTimerWithTimeInterval:10.0
                                     target:self
                                   selector:@selector(loadNextController)
                                   userInfo:nil
                                    repeats:YES];

    /*! set starting controller */
    NSArray *startingViewControllers = @[[self  viewControllerAtIndex:self.index]];

    [self setViewControllers: startingViewControllers
                   direction: UIPageViewControllerNavigationDirectionForward
                    animated: YES
                  completion: nil];
}

- (UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
    NSUInteger index = ((YSPageContentViewController*) viewController).pageIndex;
    if (index > 0 ) {
        return [self viewControllerAtIndex:index-1];
    }
    return nil;
}

- (UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
    NSUInteger index = ((YSPageContentViewController*) viewController).pageIndex;
    if (index+1 < [self.items count] ) {
        return [self viewControllerAtIndex:index+1];
    }
    return nil;
}

- (PageContentViewController *)viewControllerAtIndex:(NSUInteger)index{
    if (index < [self.items count]) {
        PageContentViewController *pageContentViewController =   [[PageContentViewController alloc]init];
        pageContentViewController.pageIndex = index;
        pageContentViewController.image = (UIImage*)self.items[index];
        return pageContentViewController;
    }
    return nil;
}

/*! set next controller */
- (void)loadNextController {
    PageContentViewController *nextViewController = [self viewControllerAtIndex:self.index++];
    if (nextViewController == nil) {
        self.index = 0;
        nextViewController = [self viewControllerAtIndex:self.index];
    }
    [self setViewControllers:@[nextViewController]
                   direction:UIPageViewControllerNavigationDirectionForward
                    animated:YES
                  completion:nil];
} 

注意：这确实有效；但是，当内部手势识别器更改控制器时，我并不总是返回正确的控制器。一路走来，我失去了对索引的追踪。我将用我完成的实现来更新它。

Answer 2

致力于@Ryan 的回答。修复了@Ryan 问题“但是，当内部手势识别器更改控制器时，我并不总是返回正确的控制器。在此过程中，我失去了对索引的跟踪。”

刚刚编辑了几行，它对我有用。想分享一下，以防有人需要。

- (void)viewDidLoad
{
[super viewDidLoad];
_pageTitles = @[@"Tips n Tricks", @"Join to learn", @"Share to get points"];
self.pageViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"PageViewController"];
self.pageViewController.dataSource = self;
self.pageViewController.delegate = self;

[NSTimer scheduledTimerWithTimeInterval:10.0
                                 target:self
                               selector:@selector(loadNextController)
                               userInfo:nil
                                repeats:YES];
PageContentViewController *startingViewController = [self viewControllerAtIndex:0];
NSArray *viewControllers = @[startingViewController];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

// Change the size of page view controller

self.pageViewController.view.frame = _containerView.frame;
self.pageControl.numberOfPages = _pageTitles.count;
self.pageControl.currentPage = 0;
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
[self addChildViewController:_pageViewController];
[self.view addSubview:_pageViewController.view];
[self.pageViewController didMoveToParentViewController:self];
[self.view bringSubviewToFront:self.pageControl];

}

PageViewController 实现的数据源方法

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    NSUInteger index = ((PageContentViewController*) viewController).pageIndex;
    if ((index == 0) || (index == NSNotFound)) {
        index = _pageTitles.count;
    }
    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.pageTitles count]) {
        index = 0;
    }
    return [self viewControllerAtIndex:index];
}
- (PageContentViewController *)viewControllerAtIndex:(NSUInteger)index
{
    if (([self.pageTitles count] == 0) || (index >= [self.pageTitles count])) {
        return nil;
    }
    PageContentViewController *pageContentViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"PageContentViewController"];
    pageContentViewController.titleText = self.pageTitles[index];
    pageContentViewController.pageIndex = index;
    return pageContentViewController;
}

实现了PageController委托的didFinishAnimating方法来获取PageViewController的当前索引并相应地更新PageControl

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
    PageContentViewController *currentViewController = pageViewController.viewControllers[0];
    currentIndex = (int)currentViewController.pageIndex;
    [self.pageControl setCurrentPage:currentIndex];
}

在最后实现的方法中更新 PageViewController 的动画

- (void)loadNextController {
    currentIndex++;
    PageContentViewController *nextViewController = [self viewControllerAtIndex:currentIndex];
    if (nextViewController == nil) {
        currentIndex = 0;
        nextViewController = [self viewControllerAtIndex:currentIndex];
    }
    [self.pageViewController setViewControllers:@[nextViewController] direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
    [self.pageControl setCurrentPage:currentIndex];
}

当前索引是全局声明的，以跟踪当前 PageViewController 的索引并相应地更新 PageController。

希望它有所帮助.. 快乐编码.. :)

Answer 3

也许你要找的方法是setViewControllers:direction:animated:completion:

当然，您需要提供希望在动画结束时可见的视图控制器。

您可以在动画设置为 YES 的情况下调用它，控制器将自动分页：)

更多信息请查看documentation