AsyncModelActor.swift

AsyncModelActor.swift

import Foundation
import SwiftData

/// The `AsyncModelActor` protocol leverages SwiftData's `@ModelActor` to safely and concurrently perform operations (CRUD) on different threads.
///
/// ### Problem:
/// By default, all `ModelActor` instances execute tasks on the thread they were initialized on. This means that if a `@ModelActor` is initialized on the main thread
/// (e.g., in a SwiftUI View or ViewModel), all its operations will run on the main thread, potentially leading to performance issues.
///
/// ### Solution:
/// To address this, you can use `Task.detached { ... }` to move the initialization of the `ModelActor` to a background thread.
/// The `AsyncModelActor` protocol provides a convenience initializer to facilitate this process.
///
/// ### Example:
/// ```swift
/// @ModelActor
/// actor MyModelActor: AsyncModelActor {
///     func performDataOperation() {
///         // This is no longer executed on main thread
///     }
/// }
///
/// @MainActor
/// struct ContentView: View {
///     @Environment(\.modelContext) var context
///
///     var body: some View {
///         Text("Hello world")
///             .task(priority: .background, performActorOperation)
///     }
///
///     @Sendable
///     func performActorOperation() async {
///         let actor = await MyModelActor(modelContainer: context.container)
///         await actor.performDataOperation()
///     }
/// }
/// ```
public protocol AsyncModelActor: Sendable {
    init(modelContainer: ModelContainer)
}

public extension AsyncModelActor {
    /// Initializes the model actor on a background thread. Actors perform their operations on the thread they're initialized on!
    init(modelContainer: ModelContainer, priority: TaskPriority?) async {
        // detached Task is required, otherwise we cannot get off the main thread
        let task = Task.detached(priority: priority) {
            // swiftlint:disable:next explicit_init
            Self.init(modelContainer: modelContainer) // Use the initializer offered by @ModelActor
        }

        self = await task.value
    }
}