ios - iOS5-在横向模式下在页面 View Controller 中翻页

我在应用程序中使用UIPageViewController和故事板。
纵向时，我正在使用以下代码从一页跳至另一页，并且工作正常。

int direction = UIPageViewControllerNavigationDirectionForward;
if ([self.modelController currentPage] < pagenum)
{
    direction = UIPageViewControllerNavigationDirectionForward;
}
else if ([self.modelController currentPage] > pagenum)
{
    direction = UIPageViewControllerNavigationDirectionReverse;
}

[self.pageViewController setViewControllers:[NSArray arrayWithObject:[self.modelController viewControllerAtIndex:pagenum storyboard:self.storyboard]] direction:direction animated:YES completion:NULL];

但是当我们处于横向模式时，相同的代码不起作用。横向时如何翻页？

最佳答案

如果您在Xcode中查看基于页面的基于模板的应用程序模板，则会发现以下UIPageViewControllerDelegate方法:

- (UIPageViewControllerSpineLocation)pageViewController:(UIPageViewController *)pageViewController spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation
{
    if (UIInterfaceOrientationIsPortrait(orientation)) {
        // In portrait orientation: Set the spine position to "min" and the page view controller's view controllers array to contain just one view controller. Setting the spine position to 'UIPageViewControllerSpineLocationMid' in landscape orientation sets the doubleSided property to YES, so set it to NO here.
        UIViewController *currentViewController = [self.pageViewController.viewControllers objectAtIndex:0];
        NSArray *viewControllers = [NSArray arrayWithObject:currentViewController];
        [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL];

        self.pageViewController.doubleSided = NO;
        return UIPageViewControllerSpineLocationMin;
    }

    // In landscape orientation: Set set the spine location to "mid" and the page view controller's view controllers array to contain two view controllers. If the current page is even, set it to contain the current and next view controllers; if it is odd, set the array to contain the previous and current view controllers.
    DataViewController *currentViewController = [self.pageViewController.viewControllers objectAtIndex:0];
    NSArray *viewControllers = nil;

    NSUInteger indexOfCurrentViewController = [self.modelController indexOfViewController:currentViewController];
    if (indexOfCurrentViewController == 0 || indexOfCurrentViewController % 2 == 0) {
        UIViewController *nextViewController = [self.modelController pageViewController:self.pageViewController viewControllerAfterViewController:currentViewController];
        viewControllers = [NSArray arrayWithObjects:currentViewController, nextViewController, nil];
    } else {
        UIViewController *previousViewController = [self.modelController pageViewController:self.pageViewController viewControllerBeforeViewController:currentViewController];
        viewControllers = [NSArray arrayWithObjects:previousViewController, currentViewController, nil];
    }
    [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL];


    return UIPageViewControllerSpineLocationMid;
}

从上述方法返回UIPageViewControllerSpineLocationMid时，您是在告诉UIPageViewController它应该期望并排显示两个UIViewController的 (即两个页面)。

这里的关键是，在调用UIPageViewController的setViewControllers:direction:animated:completion:方法时，必须传递正确数量的UIViewControllers。

显示两页？传递两个UIViewControllers。

显示一页？传递一个UIViewController。

您提供的代码绝不会将多个UIViewController传递给UIPageViewController。

如果UIPageViewControllerSpineLocation与您传递的UIViewControllers数量不匹配，它将崩溃或什么也不做。

让我知道您是否需要进一步的帮助。