Swift·Swift from optionals to SwiftUI

Concurrency

Use async/await and actors to keep shared state safe.

Beginner 14 min read Lesson 7 of 300 Challenge included

What you will be able to do

Use async functions for asynchronous work.
Use Task to start concurrent work.
Use actors for shared mutable state.
Hop to @MainActor for UI updates.

In plain English

Swift concurrency uses async functions and tasks. await suspends without blocking the thread. Actors protect mutable state. UI work belongs on the main actor.

Concurrency.swiftSwift

struct LessonService {
    func load() async throws -> [Lesson] {
        try await Task.sleep(nanoseconds: 100_000_000)
        return []
    }
}

@MainActor
final class LessonsViewModel: ObservableObject {
    @Published var lessons: [Lesson] = []
    func load() async throws { lessons = try await LessonService().load() }
}

Your turn

Load on the main actor

Easy

Annotate a view model class with @MainActor.

SWIFT · starter

final class ViewModel {

Check your understanding before moving on.

Knowledge checkQuestion 1

What does await do?

Select an answer to continue

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Lesson 7 of 300 · 0% of course