Asynchronous programming is an important aspect of modern programming, allowing us to write applications that can perform multiple tasks simultaneously. Swift, Apple’s programming language, provides two new approaches apart from GCD for asynchronous programming: Async/Await and Swift Task.

In this post, we’ll explore the differences between Async/Await and Swift Task and how to use them in your Swift code. I’ll also provide code examples to demonstrate their use.

Understanding Async/Await in Swift

Async/Await is a language feature in Swift that makes it easier to write asynchronous code by using a simpler syntax. It allows developers to write asynchronous code in a way that looks similar to synchronous code. This makes the code easier to read, write and understand.

In Swift, you can mark a function as asynchronous by using the async keyword. You can then use the await keyword to pause the function until the awaited operation is complete. This allows the function to return a value once the awaited operation has been completed.

Here is an example of using Async/Await in Swift:

func fetchData() async -> [String] {
    let url = URL(string: "https://example.com/data.json")!
    let (data, _) = try! await URLSession.shared.data(from: url)
    return String(data: data, encoding: .utf8)!.components(separatedBy: "\n")
}

async {
    let data = await fetchData()
    print(data)
}

In this example, we create a function called fetchData that returns an array of strings. We mark the function as asynchronous by using the async keyword. Inside the function, we use the await keyword to wait for the data to be fetched from the specified URL using URLSession.

We then call the fetchData function inside an async block and use the await keyword to wait for the data to be returned. Once the data is returned, we print it to the console.

Understanding Swift Task in Swift

Swift Task is another approach to asynchronous programming in Swift that provides a more powerful and flexible way to manage concurrent tasks. It allows you to create and manage tasks, which can be used to perform asynchronous operations in parallel with other tasks or the main thread.

Here is an example of using Swift Task in Swift:

let task = Task {
    for i in 0...4 {
        print("Task: \(i)")
        try await Task.sleep(nanoseconds: 1_000_000_000)
    }
}

print("Main thread")

In this example, we create a new task using the Task constructor. Inside the task, we loop through the numbers 0 to 4, printing each number to the console and sleeping for 1 second. We then print “Main thread” to the console from the main thread.

Output:

Task: 0
Main thread
Task: 1
Task: 2
Task: 3
Task: 4

The “Main thread” message is printed immediately after the Task is created. This is because the Task is running asynchronously on a separate thread, which allows the main thread to continue executing without waiting for the Task to complete.

Swift Task provides more flexibility and power than Async/Await, but it also requires more understanding of concurrency and can be more complex to use.

Conclusion

Both Async/Await and Swift Task are useful approaches for asynchronous programming in Swift. Async/Await provides a simple and intuitive syntax for writing asynchronous code that looks similar to synchronous code. Swift Task provides a more powerful and flexible way to manage concurrent tasks.

In general, you should choose the approach that best fits your needs and the specific requirements of your project. By understanding the differences between these approaches and using them in the right situations, you can write more efficient and effective asynchronous code in Swift.

Further Reading –

1. Apple Developer Documentation: Asynchronous programming with async/await

2. Apple Developer Documentation: Concurrency in Swift

3. SwiftLee: Async/Await in Swift explained with code examples

4. Hacking with Swift: Swift concurrency: Understanding async/await

These resources cover a range of topics related to asynchronous programming in Swift, including how to use async/await and Swift task, best practices for working with concurrency, and more.

Let me know if you have any queries.