Swift Wasm

Swift WASM Development Skill

Comprehensive guidance for Swift 6.2 WebAssembly workflows used by Raven.

Quick Actions

• setup: Set up Swift toolchain and WASM SDK
• build: Build the current project for WASM
• dev: Start development workflow/server
• optimize: Build an optimized production bundle
• debug: Diagnose build/runtime WASM issues
• test: Run tests and browser validation

Project Docs To Prefer

• QUICKSTART.md
• Documentation/GettingStarted.md
• Docs/bundle-size-quickstart.md

Setup Commands

brew install swiftly
swiftly install 6.2.3
swiftly use 6.2.3
swift --version

swift sdk install \
  https://download.swift.org/swift-6.2.3-release/wasm-sdk/swift-6.2.3-RELEASE/swift-6.2.3-RELEASE_wasm.artifactbundle.tar.gz \
  --checksum 394040ecd5260e68bb02f6c20aeede733b9b90702c2204e178f3e42413edad2a

swift sdk list

Build Commands

swift build --swift-sdk swift-6.2.3-RELEASE_wasm
swift build --swift-sdk swift-6.2.3-RELEASE_wasm -c release -Xswiftc -Osize

Optimization Commands

swift build \
  --swift-sdk swift-6.2.3-RELEASE_wasm \
  -c release \
  -Xswiftc -Osize \
  -Xswiftc -whole-module-optimization \
  -Xlinker --lto-O3 \
  -Xlinker --gc-sections \
  -Xlinker --strip-debug

Typical Issues

• "No available targets compatible with wasm32-unknown-wasip1": wrong Swift toolchain or missing WASM SDK
• large WASM bundle: missing -Osize / LTO / strip
• stale browser behavior: cached WASM artifact

Working Norms

• Prefer official swift.org toolchains for reproducible builds.
• For example apps, build inside each example directory when possible.
• Confirm output location under .build/wasm32-unknown-wasip1/.