This is a first look at how async/await works in Swift. To experiment with structured concurrency, this repository demonstrates how to refactor a closure based UIKit app to use async/await and Tasks instead.

This repository contains a very simple app that fetches a profile from Github. It was first implemented using the callback based URLSession, then it was refactored to use the new async/await features.

Once the repository is cloned, there are some tags with each step of this refactoring process:

• start-async-work -> contains the initial callback based code, ready to be refactored
• async-httpclient -> the first refactoring effort: make the http client perform() method an async function
• async-profileservice -> add async versions of the profile service methods
• async-viewmodel-imagefetcher -> turn the viewmodel and the imagefetcher methods into async functions
• async-call-from-controller -> initiates the async from a non-async code

Note: most refactoring was done using a toolchain from 05-14-2021, however, the most recent commits to this repository use the latest beta version of Xcode 13 (beta-4).

• Async/await proposal: https://github.com/apple/swift-evolution/blob/main/proposals/0296-async-await.md
• Structured concurrency proposal: https://github.com/apple/swift-evolution/blob/main/proposals/0304-structured-concurrency.md
• Continuations proposal: https://github.com/apple/swift-evolution/blob/main/proposals/0300-continuation.md
• Pitch regarding the initialization of concurrent work: https://forums.swift.org/t/initiating-asynchronous-work-from-synchronous-code/47714