#import <UIKit/UIKit.h>@interface ViewController : UIViewController<UIPageViewControllerDataSource, UIPageViewControllerDelegate>{    int pageIndex;}@property(strong, nonatomic) UIPageViewController *pageViewController;@end

@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];        self.view.frame = CGRectMake(0.0f, 0.0f, 300.0f, 400.0f);        //  UIPageViewControllerTransitionStylePageCurl     翻书效果    //  UIPageViewControllerTransitionStyleScroll       滑屏效果        //  UIPageViewControllerNavigationOrientationHorizontal 水平方向    //  UIPageViewControllerNavigationOrientationVertical   垂直方向    self.pageViewController = [[UIPageViewController alloc]                               initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];        self.pageViewController.dataSource = self;    self.pageViewController.delegate   = self;        UIStoryboard *mainBoard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];    UIViewController *page0 = [mainBoard instantiateViewControllerWithIdentifier:@"page1"];        NSArray *viewArray = @[page0];            [self.pageViewController setViewControllers:viewArray direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL];        [self.view addSubview:self.pageViewController.view];        pageIndex = 1;    }-(UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController{    pageIndex++;        if(pageIndex > 2){        pageIndex = 2;        return nil;    }        UIStoryboard *mainBoard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];    NSString *Id = [NSString stringWithFormat:@"page%i", pageIndex];        NSLog(@"%@", Id);        UIViewController *page = [mainBoard instantiateViewControllerWithIdentifier:Id];        return page;}-(UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController{    pageIndex--;        if(pageIndex < 0){        pageIndex = 0;        return nil;    }        UIStoryboard *mainBoard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];    NSString *Id = [NSString stringWithFormat:@"page%i", pageIndex];        NSLog(@"%@", Id);        UIViewController *page = [mainBoard instantiateViewControllerWithIdentifier:Id];        return page;}@end