问题描述

我以 Photo Scroller 为例Apple 的网站，并尝试通过复制代码来实现我自己的专辑.现在， UIScrollView 不可见.我如何让它出现?

I took the Photo Scroller example from Apple's website and tried to implement my own Album by copying the code. Now, the UIScrollView is not visible. How do I make it appear?

我所做的唯一代码更改是创建 UIPageViewController.在我的情况下，打开它的是一个 UIViewController 而不是 AppDelegate.

The only code change that I made was in creating the UIPageViewController. In my case, it's a UIViewController that is opening it and not the AppDelegate.

@implementation BasePhotoViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nil bundle:nibBundleOrNil];
    if (self) {
        // kick things off by making the first page

        PhotoViewController *pageZero = [PhotoViewController photoViewControllerForPageIndex:0];
        if (pageZero != nil)
        {
            // assign the first page to the pageViewController (our rootViewController)
            //UIPageViewController *pageViewController = (UIPageViewController *)    [[UIApplication sharedApplication] keyWindow].rootViewController;
            UIPageViewController *pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:0 navigationOrientation:0 options:nil];
            //UIPageViewController *pageViewController = (UIPageViewController *)self.parentViewController;
            pageViewController.dataSource = self;

            [pageViewController setViewControllers:@[pageZero]
                                     direction:UIPageViewControllerNavigationDirectionForward
                                      animated:NO
                                    completion:NULL];
        }
    }
    return self;
}

推荐答案

您没有将 pageViewController 的视图添加为 BasePhotoViewController 的视图的子视图.您的 BasePhotoViewController 类应如下所示.注意 viewDidLoad 中的代码.

You are not adding the pageViewController's view as a subview of BasePhotoViewController's view. Your BasePhotoViewController class should look something like this. Note the code in viewDidLoad.

BasePhotoViewController.h:

@interface BasePhotoViewController : UIViewController <UIPageViewControllerDataSource>
@property (nonatomic, strong) UIPageViewController * pageViewController;
@end

BasePhotoViewController.m:

#import "BasePhotoViewController.h"
#import "PhotoViewController.h"

@implementation BasePhotoViewController

@synthesize pageViewController;

- (id)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        PhotoViewController *pageZero = [PhotoViewController photoViewControllerForPageIndex:0];
        if (pageZero != nil)
        {
            self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:0
                                                                      navigationOrientation:0
                                                                                    options:nil];
            self.pageViewController.dataSource = self;

            [self.pageViewController setViewControllers:@[pageZero]
                                              direction:UIPageViewControllerNavigationDirectionForward
                                               animated:NO
                                             completion:NULL];
        }
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self addChildViewController:self.pageViewController];
    [self.view addSubview:self.pageViewController.view];
    [self.pageViewController didMoveToParentViewController:self];
}

# pragma mark - UIPageViewControllerDataSource

- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerBeforeViewController:(PhotoViewController *)vc
{
    NSUInteger index = vc.pageIndex;
    return [PhotoViewController photoViewControllerForPageIndex:(index - 1)];
}

- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerAfterViewController:(PhotoViewController *)vc
{
    NSUInteger index = vc.pageIndex;
    return [PhotoViewController photoViewControllerForPageIndex:(index + 1)];
}

@end

注意:我已经在 initWithCoder: 中初始化了 UIPageViewController，因为 Apple 的 Photo Scroller 代码使用情节提要.我从情节提要中删除了 UIPageViewController 并在其位置创建了一个 BasePhotoViewController.如果您没有从情节提要加载 BasePhotoViewController，则应将 initWithCoder: 中的代码移动到适当的初始化程序.

Note: I've initialised the UIPageViewController in initWithCoder: because Apple's Photo Scroller code uses a storyboard. I removed the UIPageViewController from the storyboard and created a BasePhotoViewController in its place. If you are not loading BasePhotoViewController from a storyboard, you should move the code in initWithCoder: to the appropriate initialiser.

在 github 上查看这个 示例项目.

See this sample project on github.

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