What is `TaskGroup` and when would you use it?

Answer: TaskGroup lets you run multiple async tasks in parallel and collect all their results. Use it when you have a dynamic number of parallel operations.

Code Example:

func fetchAllUsers(ids: [Int]) async throws -> [User] {
    try await withThrowingTaskGroup(of: User.self) { group in
        for id in ids {
            group.addTask {
                try await fetchUser(id: id)
            }
        }

        var users: [User] = []
        for try await user in group {
            users.append(user)
        }
        return users
    }
}

// All fetches run in parallel — much faster than sequential await
let users = try await fetchAllUsers(ids: [1, 2, 3, 4, 5])

Key Points:

• withTaskGroup for non-throwing tasks
• withThrowingTaskGroup when tasks can throw
• Results arrive in completion order, not the order tasks were added