Async functions declaration in Swift - Mini Project: Build & Apply

Async functions declaration

📖 Scenario: You are building a simple Swift program that fetches user data asynchronously, simulating a network call.

🎯 Goal: Create an async function to fetch user data and call it properly to print the result.

📋 What You'll Learn

Declare an async function named fetchUserData that returns a String

Inside fetchUserData, simulate a delay using Task.sleep

Create a main async function to call fetchUserData and store the result

Print the fetched user data in main

💡 Why This Matters

🌍 Real World

Async functions are used to perform tasks like fetching data from the internet without freezing the app interface.

💼 Career

Understanding async functions is essential for Swift developers working on apps that need smooth user experiences with network calls or long-running tasks.

1

Create the async function declaration

Declare an async function called fetchUserData that returns a String. Inside the function, return the string "User data loaded".

Swift

# Declare the async function fetchUserData
# Your code here

Need a hint?

Use func keyword, add async after parentheses, and specify -> String for return type.

2

Add a delay inside the async function

Inside the fetchUserData function, add a delay of 1 second using try? await Task.sleep(nanoseconds: 1_000_000_000) before returning the string.

Swift

func fetchUserData() async -> String {
    // Add 1 second delay here
    # Your code here
    return "User data loaded"
}

Need a hint?

Use try? await Task.sleep(nanoseconds: 1_000_000_000) to pause for 1 second.

3

Create an async main function to call fetchUserData

Declare an async function called main. Inside it, call fetchUserData() using await and store the result in a variable named userData.

Swift

func fetchUserData() async -> String {
    try? await Task.sleep(nanoseconds: 1_000_000_000)
    return "User data loaded"
}

// Declare async main function
# Your code here

Need a hint?

Use func main() async and call await fetchUserData() storing result in userData.

4

Print the fetched user data

Inside the main function, add a print statement to display the userData variable. Then, call Task { await main() } to run the async main function.

Swift

func fetchUserData() async -> String {
    try? await Task.sleep(nanoseconds: 1_000_000_000)
    return "User data loaded"
}

func main() async {
    let userData = await fetchUserData()
    // Print userData here
    # Your code here
}

// Call main function asynchronously
# Your code here

Need a hint?

Use print(userData) inside main and start it with Task { await main() }.