Asynchronous programming has become a cornerstone of modern . In the iOS ecosystem, introduced native support for asynchronous programming with Swift, including the powerful async/await pattern. In this article, we'll delve into the usage of async/await in iOS development app development Apple Understanding async/await Async/await is a programming paradigm that streamlines the execution of asynchronous code, making it appear more synchronous and readable. It eliminates the complexities of managing callbacks or completion handlers, allowing developers to write asynchronous code that same as synchronous code. With Swift's async/await, developers can efficiently handle tasks such as network requests, database queries, or file I/O without blocking the main thread Basic Usage of async/await in iOS: To create an asynchronous function, simply use the keyword in the function declaration. This signifies that the function will execute asynchronous tasks. Define an async Function: async func fetchData() async -> Data { // async operations } Within an async function, utilize the keyword to call other asynchronous functions or tasks. It suspends the current task until the awaited task is completed. Use await Inside an async Function: await func fetchImageData() async -> Data { let url = URL(string: "https://example.com/image.jpg")! do { let (data, _) = try await URLSession.shared.data(from: url) return data } catch { // Handle errors } } When calling an async function from another function, mark the calling function as async as well. This facilitates the use of for calling async functions. Mark the Caller as async: await func displayImage() async { let imageData = await fetchImageData() let image = UIImage(data: imageData) // Update UI with the image } Error handling with async/await is straightforward. Utilize and blocks to handle errors thrown within async functions. Error Handling: try catch func fetchImageDataWithThrowing(stringURL: URL) async throws -> Data { guard let url = URL(string: stringURL) else { throw NSError(domain: "Bad URL", code: 0) } let (data, _) = try await URLSession.shared.data(from: url) return data } func displayData() async { let url = "https://example.com/image.jpg" do { let data = try await fetchImageDataWithThrowing(stringURL: url) // Process data } catch { // Handle errors } } To update the UI on the main thread within async code, use to dispatch code to the main queue. Running async Code on the Main Thread: await Task { await MainActor.run { // Update UI } } or Task { @MainActor in // Update UI } Advanced Use Cases: Utilize the structure to denote the scope of an asynchronous call within synchronous code. Calling an Asynchronous Function in Synchronous Code: Task func upadeImg() { Task { let image = await fetchImageData() MainActor.run { // Update UI } } } To create an asynchronous function, simply use the construct like or . This may help you if you want to use async/await at the network layer with iOS before version 15 and after 13. Converting a Function with a Callback to Asynchronous: withCheckedContinuation withCheckedThrowingContinuation extension URLSession { func asyncDataRequest(url: URL) async throws -> Data { try await withCheckedThrowingContinuation { next in dataTask(with: url, completionHandler: { data, response, error in if let error { next.resume(throwing: error) } else if let data { next.resume(returning: data) } else { next.resume(throwing: NSError(domain: "Empty data", code: 0)) } }).resume() } } } Use constructs like or or to execute multiple asynchronous methods concurrently, reducing lines of code and improving efficiency. Running Multiple Queries in Parallel: async let withTaskGroup withThrowingTaskGroup func fetchUser() async -> User { async let imageData = await fetchImageData() async let fullName = await fetchUserFullName() return await User(avatar: imageData, fullName: fullName) } or withTaskGroup func fetchImages(imageID: [String]) async -> [Data] { await withTaskGroup(of: Data.self) { group in imageID.forEach { id in group.addTask { await fetchImageData(byID: id) } } return await group.reduce(into: [Data]()) { tmpResult, imageData in tmpResult.append(imageData) } } } Conclusion Async/await in Swift presents a powerful and readable approach to asynchronous programming in iOS applications. By following the outlined steps, developers can simplify their asynchronous code, improve app responsiveness, and leverage Swift's robust asynchronous programming capabilities to create more efficient and responsive iOS apps
