如何用View Builder实现View类型的Published变量？解决代码适配报错

问题背景 #

原代码通过DialogPresentation类管理弹窗显示状态，用枚举DialogContent封装不同弹窗视图。现尝试替换为泛型结构体DynamicDialogView后，DialogPresentation出现大量报错，以下是修复方案：

原DialogPresentation实现：

final class DialogPresentation: ObservableObject {
    @Published var isPresented = false
    @Published var dialogContent: DialogContent?
    
    func show(content: DialogContent?) {
        
        if let presentDialog = content {
            dialogContent = presentDialog
            isPresented = true
        } else {
            isPresented = false
        }
    }
}

原DialogContent枚举：

enum DialogContent: View {
    
    case contentDetail01(isPresented: Binding<Bool>, title: String)
    case contentDetail02(isPresented: Binding<Bool>)


    @ViewBuilder
    var body: some View {
        switch self {
        case .contentDetail01(let isPresented, let title):
            DemoDialogContent01(isPresented: isPresented, title: title)
        case .contentDetail02(let isPresented):
            DemoDialogContent02(isPresented: isPresented)
        }
    }
}

新的泛型DynamicDialogView：

struct DynamicDialogView<Content: View>: View {
    
    @Binding var isPresented: Bool
    let dialogContent: Content
    
    init(isPresented: Binding<Bool>,
         @ViewBuilder dialogContent: () -> Content) {
        _isPresented = isPresented
        self.dialogContent = dialogContent()
    }
}

解决步骤 #

1. 用AnyView擦除视图类型 #

泛型DynamicDialogView<Content>的类型随内部Content变化，无法直接作为具体类型存储在DialogPresentation中，需用AnyView进行类型擦除：

修改后的DialogPresentation：

final class DialogPresentation: ObservableObject {
    @Published var isPresented = false
    @Published var dialogContent: AnyView?
    
    func show<Content: View>(content: Content?) {
        if let presentDialog = content {
            dialogContent = AnyView(presentDialog)
            isPresented = true
        } else {
            isPresented = false
            dialogContent = nil
        }
    }
}

2. 优化DynamicDialogView的职责 #

原DynamicDialogView重复绑定isPresented，弹窗状态应由DialogPresentation统一管理，可简化结构体：

struct DynamicDialogView<Content: View>: View {
    let dialogContent: Content
    
    init(@ViewBuilder dialogContent: () -> Content) {
        self.dialogContent = dialogContent()
    }
    
    var body: some View {
        dialogContent
    }
}

若需在弹窗内部控制关闭，调用时直接传入DialogPresentation的绑定即可：

dialogPresenter.show(content: DynamicDialogView {
    DemoDialogContent01(isPresented: dialogPresenter.$isPresented, title: "测试弹窗")
})

3. 简化调用逻辑（可选） #

如果DynamicDialogView仅做内容包裹，可直接传入自定义弹窗视图，无需额外封装：

// 直接传入DemoDialogContent01，省略DynamicDialogView
dialogPresenter.show(content: DemoDialogContent01(isPresented: dialogPresenter.$isPresented, title: "测试弹窗"))

内容的提问来源于stack exchange，提问作者Henry P.