Apple Platforms (Swift)

Baedeker ships a Swift Package Manager package in swift/ that wraps the FFI into an idiomatic Swift API. It builds a multi-platform XCFramework so the same engine runs on macOS, iOS device, and iOS simulator.

The Swift API

let module = try BaedekerModule.compile(wasmBytes)
let instance = try BaedekerInstance(module: module)
let result = try instance.call("add", args: [.i32(20), .i32(22)])
// result == [.i32(42)]

callAsync dispatches on a background queue for non-blocking host integration.

Host functions

Host functions are Swift closures bridged through a C trampoline:

instance.registerHostFunction("env", "log") { args in
    print("guest called log:", args)
    return []
}

The trampoline retains the closure for the instance’s lifetime.

Building the XCFramework

swift/build-xcframework.sh builds three slices — macOS universal, iOS device, iOS simulator — and stitches them into a .xcframework. The package’s module.modulemap is staged so SPM can consume the static library. Run it from the repo root; the script is executable and committed.

Fuel and memory

instance.setFuel(_:), instance.memoryData(), and the memory read/write APIs mirror the FFI surface. Fuel is the primary lever for bounding untrusted guest execution on mobile.