Task and TaskGroup in iOS Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Task in Swift concurrency?

A Task is a unit of asynchronous work that runs concurrently. It allows you to perform work without blocking the main thread, like fetching data or doing calculations in the background.

intermediate

What does a TaskGroup do in Swift?

A TaskGroup lets you run multiple tasks in parallel and wait for all of them to finish. It helps manage a group of related asynchronous tasks together.

beginner

How do you create a Task in Swift?

You create a Task by calling Task { } and putting your asynchronous code inside the closure. For example: Task { await fetchData() }

intermediate

Why use TaskGroup instead of multiple separate Tasks?

TaskGroup helps you keep track of all tasks as a group, making it easier to wait for all to finish and handle their results together. It also manages cancellation and errors more cleanly.

advanced

What happens if one Task in a TaskGroup throws an error?

If a Task in a TaskGroup throws an error, the whole TaskGroup throws that error and cancels remaining tasks. This helps you handle failures early and avoid wasted work.

How do you start a new asynchronous Task in Swift?

A Task { await someAsyncFunction() }

B DispatchQueue.main.async { someAsyncFunction() }

C Thread.start { someAsyncFunction() }

D async let someAsyncFunction()

Task { } creates a new asynchronous task that runs concurrently.

What is the main benefit of using a TaskGroup?

A Automatically retry failed tasks

B Run tasks one after another

C Run tasks only on the main thread

D Run multiple tasks in parallel and wait for all to finish

TaskGroup runs multiple tasks concurrently and lets you wait for all to complete.

If one task in a TaskGroup fails, what happens?

A Only that task fails, others continue

B The whole TaskGroup throws an error and cancels remaining tasks

C The TaskGroup ignores the error

D The TaskGroup retries the failed task automatically

A failure in one task cancels the group and throws the error.

Which keyword is used to wait for a TaskGroup to finish all tasks?

A async

B yield

C await

D defer

You use await to wait for asynchronous tasks or TaskGroups to complete.

Can you add tasks dynamically inside a TaskGroup?

A Yes, you can add tasks while the group is running

B No, all tasks must be declared upfront

C Only if tasks are synchronous

D Only if tasks are on the main thread

TaskGroup allows adding tasks dynamically during its execution.

Explain how Task and TaskGroup help manage asynchronous work in Swift.

Think about how you would cook multiple dishes at once and wait for all to be ready.

Describe what happens when a task inside a TaskGroup throws an error.

Imagine if one dish burns, you stop cooking the rest.