Task groups for parallel execution in Swift - Mini Project: Build & Apply

Task groups for parallel execution

📖 Scenario: You are building a simple Swift program that fetches data from multiple sources at the same time. This helps your app work faster by doing tasks in parallel.

🎯 Goal: Learn how to use TaskGroup in Swift to run multiple tasks in parallel and collect their results.

📋 What You'll Learn

Create an array of URLs as strings

Create a variable to hold the number of URLs

Use a TaskGroup to fetch data from all URLs in parallel

Print the combined results after all tasks finish

💡 Why This Matters

🌍 Real World

Fetching data from multiple web services at the same time to improve app speed.

💼 Career

Understanding parallel execution with TaskGroup is important for building efficient Swift apps that handle multiple tasks concurrently.

1

Create the list of URLs

Create a constant array called urls with these exact string values: "https://site1.com", "https://site2.com", "https://site3.com".

Swift

# Create the array 'urls' with the given URLs
# Your code here

Need a hint?

Use square brackets [] to create an array and separate strings with commas.

2

Create a count variable

Create a constant called count that stores the number of elements in the urls array using urls.count.

Swift

let urls = ["https://site1.com", "https://site2.com", "https://site3.com"]
# Create 'count' to hold the number of URLs
# Your code here

Need a hint?

Use urls.count to get the number of items in the array.

3

Use TaskGroup to fetch data in parallel

Inside an asynchronous function called fetchAllData(), use await withTaskGroup(of: String?.self) to create a task group named group. For each url in urls, add a task to group that returns a string like "Data from \(url)". Collect all results into an array called results.

Swift

let urls = ["https://site1.com", "https://site2.com", "https://site3.com"]
let count = urls.count

func fetchAllData() async {
    // Use TaskGroup to fetch data
    // Your code here
}

Need a hint?

Use withTaskGroup to run tasks in parallel and collect their results in an array.

4

Print the combined results

Inside the fetchAllData() function, after collecting the results, print the results array using print(results). Then, call fetchAllData() from Task to run it asynchronously.

Swift

let urls = ["https://site1.com", "https://site2.com", "https://site3.com"]
let count = urls.count

func fetchAllData() async {
    let results = await withTaskGroup(of: String?.self) { group -> [String] in
        for url in urls {
            group.addTask {
                return "Data from \(url)"
            }
        }
        var collectedResults: [String] = []
        for await result in group {
            if let data = result {
                collectedResults.append(data)
            }
        }
        return collectedResults
    }
    // Print the results array
    # Your code here
}

// Call fetchAllData asynchronously
# Your code here

Need a hint?

Use print(results) to show the array. Use Task { await fetchAllData() } to run the async function.