我正在iPad上使用UIPageViewController，需要在第一页显示firstviewController，在横向布局下的下一页显示ContentViewController。
如果我将NSArray设置为两个viewControllers，应用程序会在[self.pagviewController setViewController:]处崩溃，并出现以下异常：
提供的视图控制器数量（2）与所请求的书脊位置（UIPageViewControllerSpineLocationMin）所需数量（1）不匹配
以下是代码：
#pragma mark - UIPageViewControllerDataSource Methods
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerBeforeViewController:(UIViewController *)viewController
{
NSUInteger currentIndex = [self.modelArray indexOfObject:[(ContentViewController *)viewController textContents]];
if(currentIndex == 0)
{
return nil;
}
ContentViewController *contentViewController = [[ContentViewController alloc] init];
contentViewController.textContents = [self.modelArray objectAtIndex:currentIndex - 1];
return contentViewController;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerAfterViewController:(UIViewController *)viewController
{
NSUInteger currentIndex = [self.modelArray indexOfObject:[(ContentViewController *)viewController textContents]];
if(currentIndex == self.modelArray.count-1)
{
return nil;
}
ContentViewController *contentViewController = [[ContentViewController alloc] init];
contentViewController.textContents = [self.modelArray objectAtIndex:currentIndex + 1];
return contentViewController;
}
//#pragma mark - UIPageViewControllerDelegate Methods
- (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 textContents]];
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;
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
appDelegate = (AppDelegate *) [[UIApplication sharedApplication] delegate];
//Instantiate the model array
self.modelArray = [[NSMutableArray alloc] init];
self.vcs = [[NSMutableArray alloc]init];
for (int index = 1; index <= 2 ; 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.
appDelegate.contentViewController.textContents = [self.modelArray objectAtIndex:0];
NSArray *viewControllers = [NSArray arrayWithObjects:appDelegate.firstViewController,appDelegate.contentViewController,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;
}
setViewControllers:direction:animated:completion这个方法需要传递一个数组，但是如果传递超过一个视图控制器会导致崩溃？这个方法肯定还有其他使用场景，可以用数组传入参数吗？ - Brian Morearty-setViewControllers:direction:animated:completion:接受一个数组，因此当脊柱位置设置为UIPageViewControllerSpineLocationMid时，可以传入恰好两个视图控制器。否则，只期望传入一个视图控制器。这在文档中应该更明确地指出。 - sbrun