在视图中插入实体时，SwiftUI预览不能处理核心数据

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
            .previewDevice(PreviewDevice(rawValue: "iPhone 12"))
            .previewDisplayName("iPhone 12")
    }
}

struct User {
    var name: String
    var age: Int
}

struct ContentView: View {
    var user: User
    
    var body: some View {
        VStack {
            Text(user.name)
            Text("\(user.age)")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        let user = User(name: "John Doe", age: 30)
        
        return ContentView(user: user)
            .previewDevice(PreviewDevice(rawValue: "iPhone 12"))
            .previewDisplayName("iPhone 12")
    }
}