支持不同 SwiftUI 视图类型的 UIHostingController 数组

Posted 2023-02-23

【中文标题】支持不同 SwiftUI 视图类型的 UIHostingController 数组

【英文标题】：Array of UIHostingController supporting different SwiftUI View types

【发布时间】：2021-02-05 03:27:09

【问题描述】：

我正在关注https://developer.apple.com/tutorials/swiftui/interfacing-with-uikit，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：

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

当视图类型不同时，我得到"Failed to produce diagnostic for expression; please file a bug report"：

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

---

这是我的代码：

页面视图控制器

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)")
    

【参考方案1】：

可能有一种更聪明的方法来对视图数组进行类型擦除，但也可以使用AnyView 包装不同类型的视图：

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