Swift Concurrency's Biggest Unintuitive Gotchas
Context inheritance, cascading cancellation, interleaving, and Swift 6.2
Swift Concurrency is the most powerful paradigm in the language. Consequently, it’s also really bloody hard to learn. Not only are there dozens of keywords and APIs to learn; there are also some weird behaviours that can throw you off big-time.
These unintuitive behaviours introduce footguns and WTFs-per-minute which act like Lego on the carpet of your barefoot learning journey.
There are logical design decisions behind the unintuitive behaviour. Understanding these decisions builds up your own mental model. Your mental model codifies the obscure and brings enlightenment: an intuition for the unintuitive.
Today we'll be going over:
Actor context inheritance in Tasks (and how it works under the hood)
Task hierarchy & the cascading cancellation misconception
Actor re-entrancy & interleaving, plus a very controversial question
Swift 6.2 Approachable Concurrency™ turning everything on its head again
Some of these gotchas are so misunderstood, AI will explain them completely wrong. Seriously, I checked. Since this article is members-only, they will probably continue to get it wrong. How’s that for a USP?
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