Edit: The post previsouly said yielding accessors were available only in nightly toolchains, but _read and _modify are also available in release Swift builds; they’re just _ prefixed to signify they are work-in-progress. It seems that Swift 5.6 is shaping up to a great iteration of the language and will bring a round improvements to performance-critical Swift code. I was reading through a pitch by Joe Groff on some improvements to ARC and ownership the other day when I noticed that he mentions that accessor coroutines are available in Swift trunk. …

In Swift Async Sequence extensions (part 1) I covered simple ways to create an async sequence using a custom factory method and binding a sequence to a UI control via a custom assign method. This covered the “beginning” and “end” of the data stream (so to say) but what about processing or converting the data along the way? If you draw a parallel to Combine code — how would you build custom “operators” for your async sequence? …

I’ve been trying out various ways to extend and build upon the currently available Concurrency APIs introduced in Swift 5.5 I believe the Concurrency APIs are intentionally somewhat minimal so that developers would intentionally fall back on Combine for complex tasks. Maybe I’m right or wrong but I can see how a lot of people will want to extend the Concurrency APIs to suit better their current tasks. In this post I’ll code a couple of extensions that show how to easily build your own concurrent power-ups. …

I’m incredibly happy to share that today the new raywenderlich.com book “Modern Concurrency in Swift”, that I’ve been working on, is available at swiftconcurrencybook.com! Together with editors Sandra Grauschopf, Felipe Laso-Marsetti, Richard Turton, and Shai Mishali, we’ve been working very hard to get a book out as soon as possible on the newly released in 2021 Swift Concurrency: The book is written in the classic raywenderlich.com style that mixes key pieces of theory with step-by-step instructions, guiding the readers through working on practical, real-life projects. …

After I started doing some benchmarking how different APIs perform, when used to build a simple counter, I got really interested to learn more about how the new Swift concurrency model behaves at runtime. So in this post I’ll use a couple of actors and make them do concurrent computations and check how the thread list and dispatch-queues look like in the debugger. The Test Setup I’ve prepared a super-duper simple SwiftUI app that does a bunch of floating-point multiplication and division. …

I do a lot of performance and instrumenting work and I’ve found Peter Steinberger’s post here very useful when comparing lock alternatives. As I worked with async/await and actors more and more this summer, I thought it’d be nice to put together a short post offering some basic benchmarking of actors vs. the existing synchronization mechanisms. Disclaimer Benchmarking depends heavily on the system, temporary conditions, and more. As with any amateur benchmarks, take the numbers in this post with a grain of salt. …

With the work-in-progress backport of the new Swift concurrency model all the way to iOS13, async/await and friends are getting more and more relevant for all Swift developers. So here’s a quick and simple example that showcases some of the nice features of the new concurrency model without going into much detail. Thread.sleep() vs Task.sleep() Let’s just look at the old and new sleep APIs: Thread.sleep() is the old API that blocks a thread for the given amount of seconds — it doesn’t load the CPU, the core just idles. …

Yesterday I wrote about AsyncSequence, AsyncStream and a simple plan how to bridge (or proxy) Combine publishers to the new asynchronous sequences APIs - Bridge from Combine to AsyncSequence - the plan (part 1). Today let’s put together the code as planned and see if that’s going to work out so we can easily use publishers as async sequences. CombineAsyncStream setup I’ll create a new type called CombineAsyncStream and make it conform to AsyncSequence. …

Previously, I wrote about actors in Actors part 1 and Actors part 2; this time I’m going to cover how to write a Combine operator to proxy a Combine publisher into an async sequence that you can iterate over by using a simple for loop. Note: The current version of Xcode 13 is beta 2 and I’m going to be using the latest swift.org toolchain nightly snapshot in order to make use of AsyncStream. …