在 Swift 中使用 UIPageViewController 创建两页书

Question

我正在尝试在我的 swift 应用程序中实现类似书籍的界面，其中书脊位于中心，用户可以查看两页。为此，我使用 UIPageViewController 类并创建要在屏幕上显示的 ViewController 数组。

我能够正确初始化前两页。然而，当我翻页查看第 3 页和第 4 页时，它直接转到最后一页。我使用 ViewContorllerRespresentable 将其嵌入到我的 Swift UI 中，以便在屏幕上看到它。

这是我正在使用的代码。

import SwiftUI
import UIKit
import Combine

class CustomPageViewController: UIPageViewController, UIPageViewControllerDelegate, UIPageViewControllerDataSource {

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
            guard let index = viewControllersList.firstIndex(of: viewController), index >= 2 else {
                return nil
            }
        print("currrent index is", index)
            let previousIndex = index - 2
        print("MOVING BEHIND")
        print(previousIndex+1)
        print(previousIndex)
            setViewControllers([viewControllersList[previousIndex], viewControllersList[previousIndex + 1]], direction: .reverse, animated: true){finished in
                if finished{
                    print("completed move behind operation")
                }
            }
            return nil // The system manages the transition; no need to return a single view controller.
        }

        func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
            guard let index = viewControllersList.firstIndex(of: viewController), index < viewControllersList.count - 2 else {
                return nil
            }
            print("currrent index is", index)
            let nextIndex = index + 2
            print("MOVING AHEAD")
            print(nextIndex-1)
            print(nextIndex)
            setViewControllers([viewControllersList[nextIndex-1], viewControllersList[nextIndex]], direction: .forward, animated: true){finished in
                if finished{
                    print("completed move ahead operation")
                }
            }
            return nil // The system manages the transition; no need to return a single view controller.
        }
    

    lazy var viewControllersList: [UIViewController] = []

    override func viewDidLoad() {
        super.viewDidLoad()

        self.dataSource = self
        self.delegate = self

        let firstViewController = UIViewController()
        firstViewController.view.backgroundColor = .red

        let secondViewController = UIViewController()
        secondViewController.view.backgroundColor = .green

        let thirdViewController = UIViewController()
        thirdViewController.view.backgroundColor = .blue
        
        let fourthViewController = UIViewController()
        thirdViewController.view.backgroundColor = .yellow
        
        let fifthViewController = UIViewController()
        thirdViewController.view.backgroundColor = .black
        
        let sixthViewController = UIViewController()
        thirdViewController.view.backgroundColor = .magenta

        viewControllersList = [firstViewController, secondViewController, thirdViewController, fourthViewController, fifthViewController, sixthViewController]

        setViewControllers([viewControllersList[0], viewControllersList[1]], direction: .forward, animated: true){finished in
            if finished{
                print("set initial VC")
            }
        }
    }

    

    func pageViewController(_ pageViewController: UIPageViewController, spineLocationFor interfaceOrientation: UIInterfaceOrientation) -> UIPageViewController.SpineLocation {
        
        if interfaceOrientation.isLandscape{
//            self.isDoubleSided = true
            print("INSIDE THIS BLOCK OF CODE")
            if let currentViewController = self.viewControllers?.first, let currentIndex = viewControllersList.firstIndex(of: currentViewController) {
                        let nextIndex = currentIndex + 1
                        let nextViewController = (nextIndex < viewControllersList.count) ? viewControllersList[nextIndex] : nil

                        if let nextVC = nextViewController {
                            setViewControllers([currentViewController, nextVC], direction: .forward, animated: true, completion: nil)
                        } else {
                            setViewControllers([currentViewController], direction: .forward, animated: true, completion: nil)
                        }
                    }            
            return .mid
        }
        else{
            return .min
        }
        
    }
}

// 2. PageViewControllerRepresentable
struct MyViewControllerRepresentable: UIViewControllerRepresentable {

    

    func makeUIViewController(context: Context) -> CustomPageViewController {
        let pageViewController = CustomPageViewController(transitionStyle: .pageCurl, navigationOrientation: .horizontal)
        return pageViewController
    }

    func updateUIViewController(_ uiViewController: CustomPageViewController, context: Context) {
        // Update the UIPageViewController if needed
    }

}


struct TestView : View {
 var body: some View{
     VStack{
         MyViewControllerRepresentable()
     }
}
}

我觉得我真的很接近实现它，但我错过了一个小细节。感谢您对此的帮助

Answer 1

对于函数 setViewControllers([viewControllersList[index]], ...)，仅使用数组中的 1 viewcontroller 。这已经有帮助了