18

我有一个 UIPageViewController，我只是不知道如何知道用户翻页的方向，所以我可以适当地设置页数。

谢谢沙妮

4

6 回答 6

32

正如赫加兹所说

在手势驱动转换完成后 ，调用此委托方法：

pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted:

应该澄清的部分是completed页面YES是否完全翻过以及NO页面实际上没有翻过。NO例如，当用户只是拉起页面的一角，然后将其放回原处而不翻转页面时，就会发生这种情况。

这是您要实现的概念：

- (void)pageViewController:(UIPageViewController *)pvc didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
    // If the page did not turn
    if (!completed)
    {
        // You do nothing because whatever page you thought 
        // the book was on before the gesture started is still the correct page
        return;
    }

    // This is where you would know the page number changed and handle it appropriately
    // [self sendPageChangeNotification:YES];
}
于 2012-02-05T22:31:54.523 回答
7

在手势驱动转换完成后，调用此委托方法：

pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted:

所以通过比较previousViewControllers参数，pageViewController.viewControllers你可以知道方向。

于 2012-01-15T17:01:48.453 回答
3

“基于页面的应用程序”模板提供以下两种方法：

- (NSUInteger)indexOfViewController:(DataViewController *)viewController;

给定视图控制器的查找索引的方法

- (DataViewController *)viewControllerAtIndex:(NSUInteger)index

一种在给定索引的情况下实例化视图控制器的方法。

为了制作正确的动画，您需要知道当前视图控制器的索引。基于页面的模板方法非常适合。然后，您只需比较“跳转到”索引和“当前”索引。

这里有一些代码来理解这个想法：

- (void)jumpToPage:(NSInteger)page {    
   // find current index
   DataViewController *currentViewController = (DataViewController *)[self.pageViewController.viewControllers lastObject];
   NSUInteger index = [self indexOfViewController:currentViewController];

   // choosing the correct direction
   // if the 'current' is smaller than the 'jump to' page, then choose forward
   // vice versa
   UIPageViewControllerNavigationDirection direction;
   if (index < page) {
       direction = UIPageViewControllerNavigationDirectionForward;
   } else {
       direction = UIPageViewControllerNavigationDirectionReverse;
   }

   // choose view controllers according to the orientation
   NSArray *viewControllers;
   if (UIInterfaceOrientationIsPortrait(self.interfaceOrientation)) {
       DataViewController *rightViewController = [self viewControllerAtIndex:page];
       viewControllers = [NSArray arrayWithObject:rightViewController];
   } else {
       DataViewController *rightViewController = [self viewControllerAtIndex:page];
       DataViewController *leftViewController = [self viewControllerAtIndex:page-1];
       viewControllers = [NSArray arrayWithObjects:leftViewController, rightViewController, nil];
   }

   // fire the method which actually trigger the animation
   [self.pageViewController setViewControllers:viewControllers 
                                     direction:direction 
                                      animated:YES 
                                    completion:nil];
}
于 2012-01-09T11:10:26.033 回答
2

您可以将“pageIndex”属性添加到用作页面的视图控制器中。IOW，当您为 viewControllerBeforeViewController 和 viewControllerAfterViewController 创建视图控制器时（或当您调用 setViewControllers 时），将 pageIndex 存储在这些视图控制器中，然后您可以在需要知道索引时引用它。

于 2013-01-06T22:56:08.813 回答
1

great answers for page controller handling. I found that the view controller that was added as a page will call viewWillAppear as the user slides the page into view and will also call viewDidAppear upon completion.

于 2015-03-08T21:28:09.847 回答
0

setViewControllers:当用户翻页时，将调用UIPageViewController 的方法。此方法接收一个类型的参数，该参数UIPageViewControllerNavigationDirection将为您提供所需的信息。

于 2012-01-06T01:00:33.783 回答