如何在集成 UIKit 和 Swift UI 时创建自定义更新UIViewController 行为？

Question

我有一个如下所述的视图控制器。

//
//  PageViewController.swift


import SwiftUI
import UIKit

struct PageViewController: UIViewControllerRepresentable {
    var controllers: [UIViewController]
    @Binding var currentPage: Int
    init(controllers: [UIViewController], currentPage: Binding<Int>){
        self.controllers = controllers
        self._currentPage = currentPage
    }
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    func makeUIViewController(context: Context) -> UIPageViewController {
        let pageViewController = UIPageViewController(
            transitionStyle: .scroll,
            navigationOrientation: .vertical
        )
        pageViewController.dataSource = context.coordinator
        pageViewController.delegate = context.coordinator
        return pageViewController
    }

    func updateUIViewController(_ pageViewController: UIPageViewController, context: Context) {
            pageViewController.setViewControllers(
            [controllers[currentPage]], direction: .forward, animated: true)
    }


    class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
        var parent: PageViewController
        init(_ pageViewController: PageViewController) {
            self.parent = pageViewController
        }

        func pageViewController(
            _ pageViewController: UIPageViewController,
            viewControllerBefore viewController: UIViewController) -> UIViewController?
        {
            guard let index = parent.controllers.firstIndex(of: viewController) else {
                return nil
            }
            if index == 0 {
                return nil
            }

            return parent.controllers[index - 1]
        }

        func pageViewController(
            _ pageViewController: UIPageViewController,
            viewControllerAfter viewController: UIViewController) -> UIViewController?
        {
            guard let index = parent.controllers.firstIndex(of: viewController) else {
                return nil
            }
            if index + 1 == parent.controllers.count {
                return nil
            }
            return parent.controllers[index + 1]
        }
        func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
            if completed,
                let visibleViewController = pageViewController.viewControllers?.first,
                let index = parent.controllers.firstIndex(of: visibleViewController)
            {
                parent.currentPage = index
            }
        }
    }
}

在我的 swiftUI 文件中，我有类似的内容：

struct myCoolView : View { 
    @State var currentPage: Int = 0 
    var body: some View { 
        let subViews = [UIHostingController(rootView: mySubView(currentPage: $currentPage), ...]
        return VStack{ 
            PageViewController(controllers: subViews, currentPage: $currentPage)
        }

在我的子视图中，我有按钮可以在堆栈中前后移动：

struct mySubView : View {
    @Binding var currentPage: Int

    var body: some View {
        HStack {
            Button(action: {self.currentPage -= 1}){
                Text("Go Back")
            }
            Spacer()
            Button(action: {self.currentPage += 1 }){
                Text("Go Forward")
            }
        }
    }
}

前进按钮行为正确，协调器调用激活 .forward 动画样式的 updateUIViewController。问题是后退按钮在应该调用前进时也会显示前进动画样式。

我试过几种方法来解决这个问题，但 none 其中确实有效。我真正想要的是创建一个显式触发前进或后退更新流程的扩展。有什么想法可以实现吗？

提前致谢

Answer 1

在我看来你有一个

 @State var currentPage: Int = 0

您用于许多 UIHostingController/mySubView 并且也在 PageViewController 中使用。尝试使用不同的（数组）每次使用的变量。

Answer 2

我在完全相同的示例中遇到了完全相同的问题。

我通过将可见 viewController 的索引与“currentIndex”进行比较并相应地调整方向来解决它。

func updateUIViewController(_ pageViewController: UIPageViewController, context: UIViewControllerRepresentableContext<PageViewController>) {
    
    var direction: UIPageViewController.NavigationDirection = .forward

    if let visibleViewController = pageViewController.viewControllers?.first,
        let index = controllers.firstIndex(of: visibleViewController),
        index > currentPage {
        direction = .reverse
    }

    pageViewController.setViewControllers([controllers[currentPage]], direction: direction, animated: true)
}

如何在集成 UIKit 和 Swift UI 时创建自定义更新UIViewController 行为？

How to create custom updateUIViewController behavior when integrating UIKit and Swift UI?

ios

swift

xcode

swiftui

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