swift-concurrency

Diagnose and resolve Swift concurrency issues in Swift 6.3+ projects.

Updated Apr 19, 2026

Search Tags:#concurrency #patterns #swift #async-await #sendable #actor-isolation #taskgroup

Ready to run

npx skills add https://github.com/femitz/flyby --skill swift-concurrency-femitz

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: swift-concurrency
Source: https://github.com/femitz/flyby/tree/main/.agents/skills/swift-concurrency
Command: npx skills add https://github.com/femitz/flyby --skill swift-concurrency-femitz

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Swift projects frequently encounter concurrency bugs such as Sendable conformance errors, actor-isolation warnings, and data-race risks when migrating to Swift 6.2+ concurrency. This Skill centralizes guidance to diagnose, triage, and apply modern patterns to reduce these risks and improve safety.

Core Features & Use Cases

Review, fix, and write concurrent Swift code targeting Swift 6.3+.
Apply patterns for actor isolation, Sendable safety, and structured concurrency (TaskGroup, @concurrent, nonisolated) with minimal behavior changes.
Provide migration guidance from preconcurrency to Swift 6 strict concurrency and isolated conformances.

Quick Start

Apply the Swift concurrency guidance to a sample module and begin a guided concurrency fix pass.

Frequently Asked Questions about swift-concurrency

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I fix Sendable conformance errors in Swift?▼

Sendable conformance errors are fixed by ensuring types are safe to cross actor boundaries, often by marking them Sendable or refactoring them into actors. This Skill provides comprehensive triage and review checklists to diagnose and resolve these errors safely.

How do I migrate to Swift strict concurrency without changing runtime behavior?▼

Migrating to Swift strict concurrency requires applying minimal behavior changes while adopting patterns for actor isolation and Sendable safety. This Skill provides guidance for migrating from preconcurrency to Swift 6 strict concurrency and isolated conformances safely.

What is actor isolation and how does it prevent data races?▼

Actor isolation is a concurrency mechanism that protects state from data races by serializing access to it within an actor. This Skill helps you diagnose actor-isolation warnings and apply modern patterns to reduce data-race risks in Swift projects.

Does this concurrency guidance work with Swift 6.3 and structured concurrency patterns?▼

Yes, this concurrency guidance applies to Swift projects targeting Swift 6.3+ that use actors, Sendable types, MainActor isolation, TaskGroup, and structured concurrency. It satisfies requirements for actor isolation, Sendable conformance, and Task.immediate patterns.

When should I use TaskGroup and nonisolated in my Swift code?▼

TaskGroup and nonisolated should be used when implementing structured concurrency to manage parallel tasks safely without violating actor isolation. This Skill provides patterns for applying these constructs with minimal behavior changes to reduce concurrency bugs.

Why am I getting actor-isolation warnings when calling MainActor methods?▼

Actor-isolation warnings occur when code outside an actor context attempts to access isolated state without proper asynchronous awaiting. This Skill diagnoses these warnings and provides approachable concurrency patterns to resolve them safely.