PageViewController 和方向改变

Question

我有一点关于UIPageViewControllers 的策略问题。看起来它完全符合我的要求，但有些事情我不确定。我想也许有人在那里可能有一两颗宝石可以分享。 :)

这里是这样：我想使用PageViewCtl 以纵向或横向模式显示内容，但是，无论设备的方向如何，它们都必须在同一个控制器中（即具有相同的视图）。原因是内容必须以这样一种方式（横向）可缩放，即内容的两个“页面”都可以同时缩放，而不是单独缩放。在这一点上，我真的看不出如何在PageViewCtl 中处理这件事，因为据我所知，您不能在 2 个视图控制器之间共享视图。那么有人对这个问题有任何见解吗？非常感谢！

Answer 1

这是我从 Erica Sadun 那里偷来的（https://github.com/erica/iOS-5-Cookbook）：

    // Update interface to the given page
- (void) fetchControllersForPage: (uint) requestedPage orientation: (UIInterfaceOrientation) orientation
{
    BOOL sideBySide = [self useSideBySide:orientation];
    int numberOfPagesNeeded = sideBySide ? 2 : 1;
    int currentCount = self.viewControllers.count;

    uint leftPage = requestedPage;
    if (sideBySide && (leftPage % 2)) leftPage--;

    // Only check against current page when count is appropriate
    if (currentCount && (currentCount == numberOfPagesNeeded))
    {
        if (pageNumber == requestedPage) return;
        if (pageNumber == leftPage) return;
    }

    // Decide the prevailing direction by checking the new page against the old
    UIPageViewControllerNavigationDirection direction = (requestedPage > pageNumber) ? UIPageViewControllerNavigationDirectionForward : UIPageViewControllerNavigationDirectionReverse;
    [self updatePageTo:requestedPage];

    // Update the controllers
    NSMutableArray *pageControllers = [NSMutableArray array];
    SAFE_ADD(pageControllers, [self controllerAtPage:leftPage]);    
    if (sideBySide)
        SAFE_ADD(pageControllers, [self controllerAtPage:leftPage + 1]);

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

// Entry point for external move request
- (void) moveToPage: (uint) requestedPage
{
    [self fetchControllersForPage:requestedPage orientation:(UIInterfaceOrientation)[UIDevice currentDevice].orientation];
}

#pragma mark Delegate

- (UIPageViewControllerSpineLocation)pageViewController:(UIPageViewController *)pageViewController spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation
{
    NSUInteger indexOfCurrentViewController = 0;
    if (self.viewControllers.count)
        indexOfCurrentViewController = ((UIViewController *)[self.viewControllers objectAtIndex:0]).view.tag;
    [self fetchControllersForPage:indexOfCurrentViewController orientation:orientation];

    BOOL sideBySide = [self useSideBySide:orientation];
    self.doubleSided = sideBySide;

    UIPageViewControllerSpineLocation spineLocation = sideBySide ? UIPageViewControllerSpineLocationMid : UIPageViewControllerSpineLocationMin;
    return spineLocation;
}

给她一些爱。并注意超级聪明的“if (sideBySide && (leftPage % 2)) leftPage--;”，它确保左页始终是奇数页。

-A