在页面控制器中访问多个视图控制器

Question

我在ipad中显示的视图就像一本书，单个视图显示两个视图。我想添加更多视图，以便在查看翻转的第三个和第四个视图出现并进一步显示时。我正在使用下面的代码来这样做。我将视图控制器添加到数组它在定位方法在这一行杀死“ContentViewController * currentViewController = [self.pageViewController.viewControllers objectAtIndex：0];”。

- (void)viewDidLoad 
{ 
[super viewDidLoad]; 

//Instantiate the model array 
self.modelArray = [[NSMutableArray alloc] init]; 
for (int index = 1; index <= 12 ; index++) 
{ 
    [self.modelArray addObject:[NSString stringWithFormat:@"Page %d",index]]; 
} 

//Step 1 
//Instantiate the UIPageViewController. 
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl 
                  navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil]; 

//Step 2: 
//Assign the delegate and datasource as self. 
self.pageViewController.delegate = self; 
self.pageViewController.dataSource = self; 

//Step 3: 
//Set the initial view controllers. 

ViewOne *one = [[ViewOne alloc]initWithNibName:@"ViewOne" bundle:nil]; 
viewTwo *two = [[viewTwo alloc]initWithNibName:@"ViewTwo" bundle:nil]; 

ContentViewController *contentViewController = [[ContentViewController alloc] initWithNibName:@"ContentViewController" bundle:nil]; 
contentViewController.labelContents = [self.modelArray objectAtIndex:0]; 

// NSArray *viewControllers = [NSArray arrayWithObject:contentViewController]; 
viewControllers = [NSArray arrayWithObjects:contentViewController,one,two,nil]; 

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



//Step 4: 
//ViewController containment steps 
//Add the pageViewController as the childViewController 
[self addChildViewController:self.pageViewController]; 

//Add the view of the pageViewController to the current view 
[self.view addSubview:self.pageViewController.view]; 

//Call didMoveToParentViewController: of the childViewController, the UIPageViewController instance in our case. 
[self.pageViewController didMoveToParentViewController:self];  

//Step 5: 
// set the pageViewController's frame as an inset rect. 
CGRect pageViewRect = self.view.bounds; 
pageViewRect = CGRectInset(pageViewRect, 40.0, 40.0); 
self.pageViewController.view.frame = pageViewRect; 

//Step 6: 
//Assign the gestureRecognizers property of our pageViewController to our view's gestureRecognizers property. 
self.view.gestureRecognizers = self.pageViewController.gestureRecognizers; 

} 

- (UIPageViewControllerSpineLocation)pageViewController:(UIPageViewController *)pageViewController 
       spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation 
{ 
if(UIInterfaceOrientationIsPortrait(orientation)) 
{ 
    //Set the array with only 1 view controller 
    UIViewController *currentViewController = [self.pageViewController.viewControllers objectAtIndex:0]; 
    NSArray *viewControllers = [NSArray arrayWithObject:currentViewController]; 
    [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL]; 

    //Important- Set the doubleSided property to NO. 
    self.pageViewController.doubleSided = NO; 
    //Return the spine location 
    return UIPageViewControllerSpineLocationMin; 
} 
else 
{ 


    // NSArray *viewControllers = nil; 

    ContentViewController *currentViewController = [self.pageViewController.viewControllers objectAtIndex:0]; 

    NSUInteger currentIndex = [self.modelArray indexOfObject:[(ContentViewController *)currentViewController labelContents]]; 
    if(currentIndex == 0 || currentIndex %2 == 0) 
    { 
     UIViewController *nextViewController = [self pageViewController:self.pageViewController viewControllerAfterViewController:currentViewController]; 
     viewControllers = [NSArray arrayWithObjects:currentViewController, nextViewController, nil]; 
    } 
    else 
    { 
     UIViewController *previousViewController = [self pageViewController:self.pageViewController viewControllerBeforeViewController:currentViewController]; 
     viewControllers = [NSArray arrayWithObjects:previousViewController, currentViewController, nil]; 
    } 
    //Now, set the viewControllers property of UIPageViewController 
    [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL]; 

    return UIPageViewControllerSpineLocationMid; 
} 
} 

Answer 1

你不能和你在一开始要的所有视图控制器设置UIPageViewController的viewControllers财产。

您必须为数据源实现以下方法：- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController和- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController。这提供了视图控制器在更改页面时显示。当没有更多页面显示时，您必须返回零。

因此，如果您在viewDidLoad上设置了viewControllers属性和3个元素，您实际上应该只设置它们两个，因为您只允许一次显示两个页面。