swift - 支持不同 SwiftUI View 类型的 UIHostingController 数组

Question

我正在关注 https://developer.apple.com/tutorials/swiftui/interfacing-with-uikit我正在尝试将我的页面 View 附加到 UIHostingControllers 数组，并且当我这样做时一切正常:

PageView(pages: [Text("hi"), Text("hello!")])

当 View 类型不同时，我得到 “无法为表达式生成诊断；请提交错误报告”:

PageView(pages: [Text("hi"), SomeOtherView()])

---

这是我的代码:

页面 View Controller

struct PageViewController<Page: View>: UIViewControllerRepresentable {

    var pages: [Page]
    @Binding var currentPage: Int

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

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

        return pageViewController
    }

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

    class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
        var parent: PageViewController
        var controllers = [UIViewController]()

        init(_ pageViewController: PageViewController) {
            parent = pageViewController
            controllers = parent.pages.map { UIHostingController(rootView: $0.navigationBarHidden(true)) }

            for viewController in controllers {
                viewController.view.backgroundColor = .clear
            }
        }

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

            //swiping back on page 0
            if index == 0 {
                return nil
            }
            return controllers[index - 1]
        }

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

            //swiping forward on last page
            if index + 1 == controllers.count {
                return nil
            }
            return controllers[index + 1]
        }

        func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
            if completed,
               let visibleViewController = pageViewController.viewControllers?.first,
               let index = controllers.firstIndex(of: visibleViewController) {
                parent.currentPage = index
            }
        }
    }
}

网页浏览

struct PageView<Page: View>: View {

    var pages: [Page]
    @State private var currentPage = 0

    var body: some View {
        PageViewController(pages: pages, currentPage: $currentPage)
        Text("Current page = \(currentPage)")
    }
}

Answer 1

可能有更聪明的方法来对 View 数组进行类型删除，但也可以使用 AnyView 包装不同类型的 View :

PageView(pages: [AnyView(Text("hi")), AnyView(SomeOtherView())])