ios - UIPageViewController 转换 PageCurl 与 UIScrollView 错误的页面索引

Question

发帖前我搜索了很多都没有成功:

我有 UIPageViewController，其中包含 UIViewController 数组和 PageCurl 作为过渡。

每个 UIViewController 都由 UIScrollView 和 UIWebView 组成。

加载内容后根据webview高度计算的滚动高度。

现在，当我加载 UIPageViewController 并开始在 UIViewController 之间导航时，无需滚动内容，一切正常。但是如果我滚动任何页面然后导航到下一页或上一页。它将重新显示同一页面，然后再次正常工作。

我在IOS7和IOS8上测试过:

UIPageViewController viewDidLoad 方法:

    self.pageController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
NSArray *viewControllers = [NSArray arrayWithObject:currentViewController];

    [self.pageController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

self.pageController.doubleSided = NO;

[self addChildViewController:self.pageController];
[[self view] addSubview:[self.pageController view]];
[self.pageController didMoveToParentViewController:self];

View Controller webViewDidFinishLoad:

CGSize contentSize = aWebView.scrollView.contentSize;
webView.frame = CGRectMake(0, 312, contentSize.width, contentSize.height);
scrollView.contentSize = CGSizeMake(320.f, contentSize.height+60);

编辑 下面是UIPageViewController的viewControllerBeforeViewController和viewControllerAfterViewController

的完整代码

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

    NSUInteger index = [(NewsDetailVC *)viewController index];
    self.index = index;
    NSLog(@"view before %i", index);
    if (index <= 0) {
        return nil;
    }

    index--;
    currentViewController = [self viewControllerAtIndex:index];
    return [self viewControllerAtIndex:index];

}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
    NSUInteger index = [(NewsDetailVC *)viewController index];
    NSLog(@"view after %i", index);

    if (index >= self.newsList.count -1) {
        return nil;
    }
    index++;
    currentViewController =[self viewControllerAtIndex:index];
    return [self viewControllerAtIndex:index];
}

编辑2上一页是一个包含 UITableView 的 UIViewController，当单击一个单元格时会将 Items 数组传递给 UIPageViewController 和选定的索引。currentViewController 的用途是因为我可以控制字体大小和当前 View 背景。UIPageViewController 父级是 UIViewController这是 viewControllerAtIndex 的代码:

- (NewsDetailVC *)viewControllerAtIndex:(NSUInteger)index {

    NewsDetailVC *childViewController = [[UIStoryboard storyboardWithName:@"Main_iPhone" bundle:nil] instantiateViewControllerWithIdentifier:@"NewsDetailVC"];
    childViewController.index = index;
    childViewController.selectedNews = [self.newsList objectAtIndex:index ];
    childViewController.selectedCategory = self.selectedCategory;
    return childViewController;
}

Answer 1

我在使用 UIPageViewController 时遇到了同样的问题。

viewControllerAtIndex 中显示的索引似乎不太准确。

正如上面评论中提到的其他人，在这些情况下，您应该实现委托(delegate)方法 pageViewController:willTransitionToViewControllers。

在这种方法中你应该做你的工作:

- (void)pageViewController:(UIPageViewController *)pageViewController
willTransitionToViewControllers:(NSArray *)pendingViewControllers {

    if ([pendingViewControllers count] > 0) {
        NSUInteger index = [(PageContentViewController *)
        [pendingViewControllers objectAtIndex:0] pageIndex];

    if (index == [yourArray count] - 1 || index == 0) {
      [self loadContent];
    } else {
      [self doOtherStuff];
    }
  }
}

不知何故，* viewControllerAtIndex* 被调用了几次，让您很难找到索引，但在这种方法中，索引应该是准确的。

希望对您有所帮助!