在使用FetchRequest时如何在PreviewProvider中显示示例数据

import SwiftUI
import CoreData

struct ContentView: View {
    @FetchRequest(entity: Item.entity(), sortDescriptors: []) var items: FetchedResults<Item>

    var body: some View {
        List(items, id: \.self) { item in
            Text(item.name ?? "Unknown")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        let context = PersistenceController.preview.container.viewContext
        
        // 创建示例数据
        let sampleItem = Item(context: context)
        sampleItem.name = "Sample Item"
        
        return ContentView()
            .environment(\.managedObjectContext, context)
    }
}

do {
    try context.save()
} catch {
    let nsError = error as NSError
    fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}