错误：枚举案例要求闭包符合“视图”

Question

我希望创建一个带有 SwiftUI 视图的 UIViewRepresentable 作为子视图，我有以下代码，可以将其粘贴到 Xcode 中空 SwiftUI 项目的 ContentView 上。

enum Action 现在只有一个 case，但它是一个钩子，用于添加将在 updateUIView() 中执行的其他操作。

import SwiftUI

struct LegacyView<Content: View>: UIViewRepresentable {
    enum Action {
        case idle
    }

    @Binding var action: Action
    let content: Content

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

    func makeUIView(context: Context) -> UIView {
        let hosting = UIHostingController(rootView: self.content)
        let legacyView = UIView()
        legacyView.addSubview(hosting.view)
        hosting.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        return legacyView
    }

    func updateUIView(_ uiView: UIView, context: Context) {
    }

    class Coordinator: NSObject {
        let parent: LegacyView

        init(_ parent: LegacyView) {
            self.parent = parent
        }
    }
}

struct ContentView: View {
    var body: some View {
        LegacyView(action: .constant(.idle)) {
            Text("Hello, world!")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

但是在ContentView 的body 的第一行，我收到以下错误：Enum case 'idle' requires that '() -> Text' conform to 'View'。如何解决此错误？

Answer 1

根据ContentView 中的预期用法，这里是LegacyView 的更正代码...

struct LegacyView<Content: View>: UIViewRepresentable {
    enum Action {
        case idle
    }

    @Binding var action: Action
    let content: () -> Content // << builder type

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

    func makeUIView(context: Context) -> UIView {
        let hosting = UIHostingController(rootView: self.content()) // << used builder
        let legacyView = UIView()
        legacyView.addSubview(hosting.view)
        hosting.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        return legacyView
    }

    func updateUIView(_ uiView: UIView, context: Context) {
    }

    class Coordinator: NSObject {
        let parent: LegacyView

        init(_ parent: LegacyView) {
            self.parent = parent
        }
    }
}