Swift Version Matrix

Which Swift, which Xcode, which OSes ship together — and what each Swift release introduced. Use this to answer “what’s the minimum Xcode I need?” or “when did async/await ship?”

Compatibility table

Older versions exist; you almost never write new code against them. Apps in the App Store today commonly target iOS 16 or 17 minimum, which means Swift 5.7 or 5.9 features are universally available.

What each Swift release added

Swift 6 (Sept 2024)

• Strict concurrency by default — opt-in via -strict-concurrency=complete was rolled into the default. Data race safety enforced at compile time.
• Typed throws — func f() throws(MyError). Errors are now part of the type system.
• Existential any — required for any P types where P has associated types or generics.
• Sendable inference improvements — many more types automatically become Sendable.
• Pack iteration — variadic generics finally have iteration sugar.

Swift 5.10 (Mar 2024)

• Data isolation transitions — closing the last holes in actor isolation.
• AccessLevel on imports — internal import Foo to keep transitive deps internal.

Swift 5.9 (Sept 2023)

• Macros — @attached, @freestanding. Use this for @Observable, #Preview, @Model.
• if/switch as expressions — let x = if cond { 1 } else { 2 }.
• Noncopyable types — ~Copyable constraint.
• Generic parameter packs — variadic generics minus iteration.

Swift 5.8 (Mar 2023)

• Function back-deployment — @backDeployed lets new stdlib APIs work on older OSes.
• unsafeForcedSync for Result — minor ergonomics.

Swift 5.7 (Sept 2022)

• Existential improvements — any P syntax introduced.
• Type inference for generic args — many call sites stop needing explicit generic params.
• Regex literals — /(\d+)-(\d+)/.

Swift 5.5 (Sept 2021) — the big one

• async/await — structured concurrency arrives.
• Actors — actor MyType { ... }.
• Task and TaskGroup.
• @MainActor.
• async let.
• AsyncSequence.

Everything before 5.5 is “pre-concurrency Swift” — it works, but Combine and callback-based APIs dominated.

Swift 5.3 (Sept 2020)

• SwiftPM resources — bundle assets in a package.
• Multi-pattern catch — catch ErrorA, ErrorB.
• @main — single attribute for app entry point.

Mapping versions to “what can I use?”

When deciding minimum iOS version for an app:

• iOS 17+ (Swift 5.9): use Macros, Observation, SwiftData. Strongly recommended for new apps in 2024+.
• iOS 16+ (Swift 5.7): regex literals, existential any. No SwiftData; use SwiftUI navigation NavigationStack.
• iOS 15+ (Swift 5.5): async/await available, but AsyncSequence ergonomics are weaker. No Observable macro.
• iOS 14+ (Swift 5.3): pre-concurrency. Use Combine or callbacks. Last refuge for legacy apps.

App Store submission Xcode requirement

Apple periodically raises the minimum Xcode required for App Store submissions. As of late 2024, submissions require Xcode 15.4 or later. Check Apple’s submission requirements before shipping; this changes ~annually.

When to target what

Don’t target older than necessary — every supported version adds testing surface and #available checks.