How can I get data from SwiftData on Widget (macOS)

Question

I want to fetch data from SwiftData on Widget but it returns empty data even though there are some data. How can I fetch data correctly? Do I need to setup something in widget target to communicate with the main macOS app?

struct Provider: AppIntentTimelineProvider {
    @MainActor func placeholder(in context: Context) -> SimpleEntry {
        SimpleEntry(date: Date(), configuration: ConfigurationAppIntent(), items: getItems())
    }

    func snapshot(for configuration: ConfigurationAppIntent, in context: Context) async -> SimpleEntry {
        await SimpleEntry(date: Date(), configuration: configuration, items: getItems())
    }
    
    func timeline(for configuration: ConfigurationAppIntent, in context: Context) async -> Timeline<SimpleEntry> {
        return Timeline(entries: [await SimpleEntry(date: Date(), configuration: configuration, items: getItems())], policy: .after(.now.advanced(by: 60 * 10)))
    }

    @MainActor func getItems() -> [Item] {
        let container: ModelContainer(for: Item.self)
        let descripter = FetchDescriptor<Item>()
        let items = try? container.mainContext.fetch(descripter)
        return items ?? []
    }
}

struct SimpleEntry: TimelineEntry {
    let date: Date
    let configuration: ConfigurationAppIntent
    let items: [Item]
}

Answer 1

I just had to set App Groups for macOS app and widget targets

This is the way to add App groups https://useyourloaf.com/blog/sharing-data-with-a-widget/