SwiftData (iOS 17+)

import SwiftData
 
@Model
class Todo {
    var title: String
    var isComplete: Bool
    var createdAt: Date
    
    init(title: String) {
        self.title = title
        self.isComplete = false
        self.createdAt = Date()
    }
}

@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(for: [Todo.self])
    }
}

struct TodoList: View {
    @Query var todos: [Todo]
    
    var body: some View {
        List(todos) { todo in
            Text(todo.title)
        }
    }
}
 
// With sort
@Query(sort: \Todo.createdAt, order: .reverse)
var todos: [Todo]
 
// With filter
@Query(filter: #Predicate<Todo> { !$0.isComplete })
var incompleteTodos: [Todo]

struct TodoList: View {
    @Environment(\.modelContext) var context
    @Query var todos: [Todo]
    
    func addTodo() {
        let todo = Todo(title: "New Task")
        context.insert(todo)
    }
    
    func deleteTodo(_ todo: Todo) {
        context.delete(todo)
    }
}

@Model
class Category {
    var name: String
    @Relationship(deleteRule: .cascade)
    var todos: [Todo] = []
}
 
@Model
class Todo {
    var title: String
    var category: Category?
}