UIPageViewController 委托、数据源和接口错误

Question

我正在开发一个使用 UIPageViewController 的应用程序，以便我可以从左向右滑动以浏览页面 (ViewControllers)。自从我的原始帖子以来，我已经编写了代码。但我收到三个错误。

错误 1：在“IntroPages”类型的对象上找不到属性“delegate” 错误 2：在“IntroPages”类型的对象上找不到属性“dataSource” 错误 3：“IntroPages”没有可见的@interface 声明选择器“setViewControllers:direction:animated:completion:”

所有三个错误都在 viewDidLoad 的第一部分（部分在 {} 大括号中）。前两个是 viewDidLoad 下面的代码，第三个是 5 行。

委托和数据源在 .h 文件中被引用。为什么他们没有被发现？为什么“IntroPages”没有可见的@interface？

代码如下。

IntroPages.h

#import <UIKit/UIKit.h>

@interface IntroPages : UIViewController
<UIPageViewControllerDelegate, UIPageViewControllerDataSource>

@end

IntroPages.m

#import "IntroPages.h"

@interface IntroPages ()

@end

@implementation IntroPages
{
    NSArray *myViewControllers;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.delegate = self; 
    self.dataSource = self;

    UIViewController *p1 = [self.storyboard
                            instantiateViewControllerWithIdentifier:@"Intro1ID"];
    UIViewController *p2 = [self.storyboard
                            instantiateViewControllerWithIdentifier:@"Intro2ID"];
    UIViewController *p3 = [self.storyboard
                            instantiateViewControllerWithIdentifier:@"Intro3ID"];
    UIViewController *p4 = [self.storyboard
                            instantiateViewControllerWithIdentifier:@"Intro4ID"];

    myViewControllers = @[p1,p2,p3,p4];

    [self setViewControllers:@[p1]
                   direction:UIPageViewControllerNavigationDirectionForward
                    animated:NO completion:nil];

    NSLog(@"loaded!");
}


@end

Answer 1

如果页面不是太多，您可以创建一个视图控制器数组，其中包含一组 id，如下所示：

// assuming this
@property (strong, nonatomic) IBOutlet UIPageViewController *pageViewController;
@property (strong, nonatomic) NSArray *pages;

// then, to setup, say these are the page ids...
NSArray *vcIds = @[ @"id0", @"id1", ... ];
self.pages = [NSMutableArray array];

for (NSString *vcId in vcIds) {
    UIViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:vcId];
    [self.pages addObject:vc];
}

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

UIPageViewControllerDataSource 在给定 vc 之前和之后请求视图控制器。通过在 pages 数组中查找传递的 vc 得到正确的结果...

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
    NSUInteger index = [self.pages indexOfObject:viewController];
    return (index)? self.pages[index-1] : 0;
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
    NSUInteger index = [self.pages indexOfObject:viewController];
    return (index<self.pages.count-1)? self.pages[index+1] : self.pages[self.pages.count-1];
}