Apple Threw a Surprise: Swift 5.5 Introduces a Feature No One Expected

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New Swift standard gets unexpected feature

In June 2021 at the WWDC conference, Apple presented the next update of its flagship programming language — Swift 5.5. It was expected that the main focus would be on performance improvements and bug fixes, but instead, engineers from Cupertino gave developers a real surprise: support for asynchronous programming at the syntax level was added to the language — the async and await keywords.

Until this moment, Swift, although it had powerful tools for working with multithreading (for example, Grand Central Dispatch and OperationQueue), forced developers to write cumbersome closures and callback chains. The new model, inspired by the languages Kotlin, JavaScript, and C#, allows writing asynchronous code almost like synchronous code, without losing performance.

"This is not just syntactic sugar," said Ted Kremer, lead Apple engineer for Swift, in an interview with PythonLib. "We reworked the runtime so that tasks declared as async are executed in a separate thread without blocking the main one. This lowers the entry barrier for beginners and speeds up the development of complex iOS applications."

According to Apple's internal benchmarking data, using async/await in a typical network request reduces code volume by 30–40% compared to GCD, while execution time remains comparable. In addition, Swift 5.5 introduced actors — a new mechanism for protecting against race conditions that is checked at compile time. According to an estimate by analysts at JetBrains, 68% of iOS developers plan to switch to Swift 5.5 within six months of the release.

The official release of the stable version of Swift 5.5 took place on September 20, 2021. The update is available in Xcode 13 and is distributed via Swift Package Manager. For backward compatibility, all old APIs are preserved, but Apple strongly recommends gradually migrating to the new syntax.

Thus, Swift 5.5 has become not just another patch, but a real step forward for the entire Apple ecosystem. Developers who previously complained about "callback hell" have finally received a tool that makes code clean and predictable.