Swift 6.2 and Xcode 27: Concurrency, Testing, and Agentic Coding

Swift 6.2 Concurrency in Real Codebases

Swift 6.2 pushes data-race safety from warnings to errors in more modules. @MainActor boundaries around UI, actor-isolated services for networking, and Sendable conformance on models crossing tasks are no longer optional niceties — they block release builds when strict mode is on.

Our migration approach: enable strict concurrency per module, fix the top twenty files by warning count, add swift-testing alongside XCTest for new code. Legacy Objective-C bridges may need @unchecked Sendable wrappers — document every one.

Xcode 27 Agentic Coding — Use With Guardrails

Xcode 27's integrated agents can plan refactors, generate App Intents boilerplate, and run multi-turn test fixes. Productive for scaffolding; dangerous for security-sensitive code without review. We require human review on authentication, payments, and data deletion paths — same as any Copilot policy.

Point agents at your ARCHITECTURE.md and intent schema docs for better output. Generic prompts produce generic Swift.

CI/CD Updates for iOS 27

Move CI macOS runners to Xcode 27 before September public release. Cache SwiftPM and derived data aggressively — clean builds are slower. Run App Intents tests on device farms with at least one iOS 27 beta device per supported form factor.