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Through the Ages: Apple Concurrency APIs

Through the Ages: Apple Concurrency APIs

Play with working code from 1977 to the modern day

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Jacob Bartlett
Jun 24, 2025
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Through the Ages: Apple Concurrency APIs
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(Until Jacob’s Tech Tavern came along), Swift Concurrency was the best thing to happen to the Swift Language.

It’s a well-designed, modern paradigm that allows you to perform the most complicated kinds of parallel processing and multitasking like it’s nothing.

But it was a long road to get here.

Apple doesn’t one-shot their APIs. They are in the oven a long time, and it’s taken them 49 years to hone their concurrency tooling into the fine-tuned magic at our fingertips.

Their first breakout machine, the Apple ][, released in 1977. It was a simpler time.

Woz couldn’t just implement GOTO await into BASIC. He’d look you in the eye, and say, “Parallelism? This thing only has one core! Do I look like a millionaire to you!?”

So humble.

Modern threading paradigms we enjoy today simply didn’t exist, because the machines were so primitive. As time went on, computers got more powerful, and our tools evolved.

The internet ate the world, iPhones ate the internet, and now we watch cat videos on devices that process instructions faster than every computer in 1985, put together. With great power comes great parallelism, more complex demands from our users, and greater demand for ergonomic tooling.

Today we’re going to travel through time and look at the concurrency APIs that were available to Apple platform developers. We’ll run real working code from each era, and ultimately understand how the concurrency tools of today arrived at where they are.

  • 1977: Apple ][ and Primitive Scheduling

  • 1984: Macintosh and Multitasking

  • 1989: NeXTSTEP and POSIX Threads

  • 2009: OS X and Grand Central Dispatch

  • 2021: Swift Concurrency and a multi-platform future

Subscribe to Jacob’s Tech Tavern for free to get ludicrously in-depth articles on iOS, Swift, tech, & indie projects in your inbox every week.

Paid subscribers get full access to this article, plus my full Elite Hacks library. You’ll also get all my long-form content 3 weeks before anyone else.

That’s right, I rebranded my paid content to Elite Hacks. I finally have the confidence to put my best work behind the paywall, and clocking in at 2,500 words, it felt silly to continue calling these ‘Quick Hacks’.

My best work? Maybe. Who knows? You will, if you pay me £7 per month.

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You’re welcome to read the other entries in my “Through The Ages” series, both free:

  • Through the Ages: Apple CPU Architecture

  • Through the Ages: Apple Animation APIs

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