Swift 6.4

Swift 6.4 landed alongside Xcode 27 and the iOS 26 platforms at WWDC26. I upgraded a mid-sized app to check whether Apple really listened, and the ergonomics work is the story here more than any single headline feature.

Everyday Ergonomics

The release is built around removing everyday friction. Function-call ergonomics get real attention: several common patterns now take fewer keystrokes, notably around async functions and succinct calls that previously required explicit argument wrapper. Short-form async functions lose boilerplate that annoyed every second project I open.

Faster and Safer C Interop

The WWDC session walks through porting sections of a C codebase to Swift, and the interop path is visibly smoother. Better handling of C pointers and headers reduces the unsafe bridging you used to write by hand. Improved ownership and concurrency control round out the high-performance story.

Warning Control and UniqueArray

Warning control gets granular, so you can silence specific diagnostics where a global suppress is too blunt. SE-0527 introduces the UniqueArray type, a value type backed by storage semantics that give you range checks and uniqueness guarantees without the overhead of a general-purpose collection.

The Upgrade Verdict

I touched no concurrency code and nothing broke at build time. That is the best sign for a point release. Verdict: worth it now, and the ergonomics alone justify the jump for anyone still on older patch versions.