如何修复Swift Screen Time API错误:类型为“Button<Text>”的值没有成员“familyActivityPicker”

我一直在遵循WWDC 21中关于如何使用屏幕时间API的教程。本教程提供了以下代码:

import FamilyControls
import SwiftUI

@StateObject var model = MyModel()
@State var isPresented = false

var body: some View {
    Button("Select Apps to Discourage") {
        isPresented = true
    }
    .familyActivityPicker(isPresented: $isPresented, 
                          selection: $model.selectionToDiscourage)
}

我尝试在我的应用程序中使用它:

import SwiftUI
import SwiftData
import FamilyControls

struct AppSelectionButton: View {
    @Binding var isPresented: Bool
    @ObservedObject var model: MyModel

    var body: some View {
        Button("Select Apps to Discourage") {
            isPresented = true
        }
        .familyActivityPicker(isPresented: $isPresented,
                              selection: $model.selectionToDiscourage)
    }
}

class MyModel: ObservableObject {
    @Published var selectionToDiscourage: FamilyActivitySelection

    init() {
        self.selectionToDiscourage = FamilyActivitySelection()
    }
}

但当我这样做时,我得到了错误“Button类型的值没有成员familyActivePicker”。

我也试过:

struct ExampleView: View {
    @@Published var selection = FamilyActivitySelection()

    var body: some View {
        VStack {
            Image(systemName: "eye")
                .font(.system(size: 76.0))
                .padding()

            FamilyActivityPicker(selection: $selection)

            Image(systemName: "hourglass")
                .font(.system(size: 76.0))
                .padding()
        }
        .onChange(of: selection) { newSelection in
            let applications = selection.applications
            let categories = selection.categories
            let webDomains = selection.webDomains
        }
    }
}

但它仍然不起作用。

我的目标是iOS 18.1。

是什么导致了这个错误?