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Overview

Approachable Concurrency

Approachable Concurrency is a real build setting in Xcode 26 that enables a set of compiler flags to make concurrency more accessible. It comes from the vision document published by the Swift team in February 2025.

💡It's a real setting, not just a concept. Approachable Concurrency is completely independent from Default Actor Isolation. They are two separate knobs in Xcode.

The 5 feature flags

What gets enabled when setting Approachable Concurrency = Yes

NonisolatedNonsendingByDefault

SE-0461 · Async nonisolated inherits the caller's actor

New in 6.2

InferIsolatedConformances

SE-0470 · Actor-isolated conformances

New in 6.2

InferSendableFromCaptures

SE-0418 · Automatic @Sendable inference

Already in Swift 6

GlobalActorIsolatedTypesUsability

SE-0434 · Better usability for @MainActor types

Already in Swift 6

DisableOutwardActorInference

SE-0401 · Property wrappers don't propagate isolation

Already in Swift 6

⚠️In Swift 6 language mode, only 2 flags change: InferIsolatedConformances and NonisolatedNonsendingByDefault. The other 3 are already enabled by default.

How to enable it in a Swift Package

Package.swift

// swift-tools-version: 6.2

.target(
    name: "YourTarget",
    swiftSettings: [
        // Only if you want MainActor default (optional):
        // .defaultIsolation(MainActor.self),

        // Approachable Concurrency flags:
        .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
        .enableUpcomingFeature("InferIsolatedConformances"),
        .enableUpcomingFeature("InferSendableFromCaptures"),
        .enableUpcomingFeature("GlobalActorIsolatedTypesUsability"),
        .enableUpcomingFeature("DisableOutwardActorInference")
    ]
)

Verified sources: Apple Swift Evolution (SE-0461, SE-0466, SE-0470, SE-0434, SE-0401) · Hacking with Swift (Paul Hudson) · SwiftLee (Antoine van der Lee) · Donny Wals · Julio César Fernández · Apple Coding Academy · Swift Forums

Complete Swift 6.2 Guide: Approachable Concurrency Explained

Overview

The 5 feature flags

How to enable it in a Swift Package

Related posts

Development Resources