Structured Concurrency

Lesson - 8 Structured Concurrency(Swift Concurrency)

So far we have created independent tasks.

Task {
    // task
}

what if we wants task to be have child-parent relationship?
That's where structured concurrency comes in. Here parents manages the children's.

This give us important guarantees around:

• Life Time
• Cancellation
• Errors
• Completion

We will start with simple concurrency tool async let

suppose we have:

func fetchUser() async -> String {
    return "Armaan"
}

func fetchPosts() async -> [String] {
    return ["Post 1", "Post 2"]
}

we can do it them sequentially

fetchUser
████████
↓
done
↓
fetchPosts
████████
↓
done

If each task takes 2 seconds then roughly it would take 4 seconds.
But these operations do not depend on each other.

We can run them concurrently.

async let user = fetchUser()
async let posts = fetchPosts()


let result = await(user, posts)

Now,

fetchUser
████████
↓
└──────── done

fetchPosts
████████
↓
└──────── done

They can make progress concurrently. If each takes roughly 2 seconds it would take approximately 2 seconds rather than 4 seconds.