cranpose-storekit

StoreKit 2 in-app purchases for Cranpose, implementing the cross-platform [cranpose_services::purchases] API on iOS and macOS.

use cranpose_services::purchases::{self, StorePhase};

cranpose_storekit::register();
purchases::configure(&["com.example.app.pro"]);

// Read the snapshot from the frame loop — the store answers asynchronously.
let state = purchases::store_state();
let unlocked = match state.phase {
    StorePhase::Unavailable => true, // no store on this platform: free here
    _ => state.owns("com.example.app.pro"),
};
let price = state.display_price("com.example.app.pro").unwrap_or("");

On non-Apple targets register() is a no-op, the build script does nothing, and the crate compiles away — so it can sit in an Android, desktop or web dependency graph unchanged.

How it works

StoreKit 2 is Swift-only: Product, Transaction, Transaction.updates and the on-device JWS verification have no Objective-C surface. The build script compiles swift/storekit.swift with swiftc -emit-library -static and links the archive with +whole-archive so Swift's autolink records survive.

Two things about that link are worth knowing before changing it:

• cargo:rustc-link-arg does not propagate from a dependency's build script. An rlib is never linked, so a link-arg emitted here silently vanishes and the build stays green with the symbol missing. Only rustc-link-lib and rustc-link-search reach the final binary; the build script uses those exclusively.
• Swift autolinking needs the toolchain path as well as the SDK path. libswiftCompatibility56.a and libswiftCompatibilityPacks.a live in the Xcode toolchain, not the SDK. Without that search path the link fails in a way that reads as "autolinking is broken".

There is no Frameworks/ copy step and no @rpath: the Swift runtime has shipped in the OS since iOS 12.2, so the SDK's .tbd stubs are all the linker needs.

Requirements

• IPHONEOS_DEPLOYMENT_TARGET=15.0 (or MACOSX_DEPLOYMENT_TARGET=12.0) must be exported. The build script refuses to run without it, on purpose. Swift's concurrency runtime has been in the OS only since iOS 15 / macOS 12; link below that and libswift_Concurrency resolves against Xcode's Swift 5.5 back-deployment copy, whose install name is @rpath/…. The build stays green and the app dies at launch with "Library not loaded". rustc reads the same variable when it links the final binary, which is why the build script insists rather than defaulting.
• Xcode installed and selected (xcode-select -p), for swiftc and xcrun.

Verifying a link

export IPHONEOS_DEPLOYMENT_TARGET=15.0
cargo build -p cranpose-storekit --example link_check --target aarch64-apple-ios
otool -L target/aarch64-apple-ios/debug/examples/link_check | grep swift

Every line must be an absolute /usr/lib/swift/… path. A single @rpath/… entry means the deployment target slipped and the binary will not launch. Measured on device, simulator and macOS host with Xcode 26.5: all absolute.

License

Apache-2.0