Question

这是我的第一篇文章，所以如果我能改进我的问题，我愿意接受反馈。

我一直在研究Swift大约一年了，我正在尝试构建一个使用UIPageViewController制作一个模仿书籍体验的应用程序的应用程序。用户可以根据需要创建任意数量的页面。现在，我有一个带有imageView和textView的模板UIViewController。用户按下＆＃34; +＆＃34;按钮添加下一页，它应该显示为预先设置的空白imageView（他们可以设置）和一个空白的textView。

规格：我使用CoreData保存用户信息。

问题： 我创建了一组新的页面。然后我添加一个图像和一些文字。我轻拍＆＃34; +＆＃34;并在下一页上做同样的事情。当我点击＆＃34; +＆＃34;之后，下一页和之后的每个页面都会复制上一页中的图像和文本，而不是空页。

以下是我的网页应如何运行的逻辑。

extension BookPageViewController: UIPageViewControllerDataSource {

  func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {

      guard let viewControllerIndex = storyPageViewControllers.index(of: viewController as! TemplateViewController) else { return nil }

      if viewControllerIndex == 0 { return nil } // Page won't scroll below first page.

      let previousIndex = viewControllerIndex - 1

      guard storyPageViewControllers.count > previousIndex else { return nil }
      currentPage = Double(previousIndex)

      return storyPageViewControllers[previousIndex]
  }

  func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {

      guard let viewControllerIndex = storyPageViewControllers.index(of: viewController as! TemplateViewController) else { return nil }

      let nextIndex = viewControllerIndex + 1
      let storyPageViewControllersCount = storyPageViewControllers.count

      guard storyPageViewControllersCount != nextIndex else { return nil }

      guard storyPageViewControllersCount > nextIndex else { return nil }
      currentPage = Double(nextIndex)
      return storyPageViewControllers[nextIndex]
  }

  func presentationCount(for pageViewController: UIPageViewController) -> Int {
      return storyPageViewControllers.count
  }



  func presentationIndex(for pageViewController: UIPageViewController) -> Int {
      guard let firstViewController = viewControllers?.first,
          let firstViewControllerIndex = storyPageViewControllers.index(of: firstViewController as! TemplateViewController) else
      { return 0 }

      return firstViewControllerIndex
  }
}

这是＆＃34; +＆＃34;的IBAction。按钮：

guard let book = book else { return }
PageController.shared.createPageWith(text: "", pageNumber: currentPage + 1.0, image: #imageLiteral(resourceName: "ImageViewPlaceHolder"), book: book)

updateStoryPageViewControllers()

setViewControllers([storyPageViewControllers[Int(currentPage) + 1]], direction: .forward, animated: true, completion: nil)

更新：根据要求，以下是评论者要求的功能。

func updateStoryPageViewControllers() {

    // Mark: - RETURN HERE TO TALK TO SPENCER ABOUT FIXING THE VC UPDATING.

    // Make a check to see which pages already have view controllers, and only make a new view controller for the pages that don't.

    guard let book = book else { return }

    // Create an array of view controllers to store the page VCs being instantiated
    var temporaryViewControllers: [TemplateViewController] = []

    // Loop through the books pages, and make a view controller for each
    if let pages = book.pages?.array as? [Page], pages.count > 0 {
        for page in pages {

            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            guard let pageVC = storyboard.instantiateViewController(withIdentifier: "TemplateViewController") as? TemplateViewController else { break }

            pageVC.page = page
            temporaryViewControllers.append(pageVC)
        }
    } else {

        //FIXME: - Default image set here.
        guard let page = PageController.shared.createPageWith(text: "", pageNumber: 0, image: #imageLiteral(resourceName: "ImageViewPlaceHolder"), book: book) else { return }
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        guard let pageVC = storyboard.instantiateViewController(withIdentifier: "TemplateViewController") as? TemplateViewController else { return }
        pageVC.page = page

        temporaryViewControllers.append(pageVC)
    }
    // Set the self.storyPageViewControllers array to the array you just made and filled.
    self.storyPageViewControllers = temporaryViewControllers
}

以下是createPageWith方法的代码：

@discardableResult func createPageWith(text: String, pageNumber: Double, image: UIImage, book: Book) -> Page? {
    //Turns the UIImage into data to be saved in CoreData.
    guard let data = UIImageJPEGRepresentation(image, 0.8) else { return nil }

    let page = Page(text: text, pageNumber: pageNumber, photoData: data, book: book)

    BookController.shared.saveToPersistentStore()

    return page
}

如何让我的UIPageViewController加载正确的索引？斯威夫特3

0 个答案: