I am trying to create a SwiftData app using NavigationSplitView. I started with a new SwiftData project for IOS. I updated ContentView like this: import SwiftUI import SwiftData struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var items: [Item] @State private var selection: Item? var body: some View { NavigationSplitView { List(selection: $selection) { ForEach(items) { item in Text(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard)) } .onDelete(perform: deleteItems) } .toolbar { ToolbarItem(placement: .navigationBarTrailing) { EditButton() } ToolbarItem { Button(action: addItem) { Label("Add Item", systemImage: "plus") } } } } detail: { DetailView(selection: selection) } .navigationSplitViewStyle(.balanced) } private func addItem() { withAnimation { let newItem = Item(timestamp: Date()) modelContext.insert(newItem) } } private func deleteItems(offsets: IndexSet) { withAnimation { for index in offsets { modelContext.delete(items[index]) } } } } #Preview { ContentView() .modelContainer(for: Item.self, inMemory: true) } and then I created DetailView.swift: import SwiftUI import SwiftData struct DetailView: View { var selection: Item? var body: some View { if let item = selection { Text("Item at \(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard))") } else { Text("nothing selected") } } } #Preview { return DetailView(selection: Item(timestamp: Date())) .modelContainer(for: Item.self, inMemory: true) } Item.swift is unchanged for how it was generated in the new project: import Foundation import SwiftData @Model final class Item { var timestamp: Date init(timestamp: Date) { self.timestamp = timestamp } } But when I add the declaration of an Item in the #preview of DetailView, the project no longer builds: /var/folders/9j/8r6qn35j5jjf0gm3crp6gynw0000gn/T/swift-generated-sources/@__swiftmacro_12navSplitView4Item5ModelfMc_.swift:1:1 Type 'Item' does not conform to protocol 'PersistentModel' What do I need to do to pass these @Model objects around as parameter?