支持不同 SwiftUI 视图类型的 UIHostingController 数组 [英] Array of UIHostingController supporting different SwiftUI View types

问题描述

我正在关注 https://developer.apple.com/tutorials/swiftui/interface-with-uikit 并且我正在尝试将我的页面视图附加到 UIHostingControllers 数组中，而当我这样做时一切正常:

I'm following https://developer.apple.com/tutorials/swiftui/interfacing-with-uikit and I'm trying to append my page views to an array of UIHostingControllers and while everything works when I do:

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

我收到 "无法生成表达式的诊断信息；当视图类型不同时，请提交错误报告:

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

---

这是我的代码:

---

Here is my code:

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
            }
        }
    }
}

页面视图

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)")
    }
}

推荐答案

可能有一种更聪明的方法来对视图数组进行类型擦除，但同样有效的方法是用 AnyView:

There may be a more clever way to do the type erasure on the array of views, but what will also work is just wrapping the different typed Views with AnyView:

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

这篇关于支持不同 SwiftUI 视图类型的 UIHostingController 数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！