in_app_purchase_watchos

The watchOS implementation of in_app_purchase, over dart:ffi (StoreKit). Started from a flutter-watchos plugin port scaffold of in_app_purchase_storekit; see PORTING_REPORT.md for the API map.

Usage

Add this package alongside in_app_purchase:

dependencies:
  in_app_purchase: ^<latest>
  in_app_purchase_watchos: ^0.0.1

That is all. Use the standard in_app_purchase API — no watchOS-specific setup:

final bool available = await InAppPurchase.instance.isAvailable();
final ProductDetailsResponse response =
    await InAppPurchase.instance.queryProductDetails(<String>{'my_product'});
Why this package does something unusual at registration

The app-facing in_app_purchase package does not honour the plugin registrant: it picks an implementation from defaultTargetPlatform and assigns it unconditionally the first time InAppPurchase.instance is read. watchOS reports as TargetPlatform.iOS, so that would install the iOS StoreKit method-channel implementation over this one — and method channels do not exist on watchOS, so every call would fail with channel-error.

That selection runs exactly once and is then memoised, so registerWith() triggers it during plugin registration and installs this implementation afterwards. The app's later reads return the memoised object without re-registering, and every InAppPurchase method resolves InAppPurchasePlatform.instance at call time, so this implementation stays live.

Because the registrant runs before main() creates the binding, the first attempt can fail (upstream installs a pigeon handler, which needs a binding); it is retried on subsequent event-loop turns, well before any widget builds.

example/integration_test/registration_test.dart verifies this end to end on a watch: the plain InAppPurchase API reaches StoreKit through FFI with no app-side setup.

Status

Working, and verified end to end on a watch (see below). Versioned 0.0.1 while the package settles. StoreKit purchasing is available on watchOS (from 6.2), but the StoreKit UI surfaces (SKStoreProductViewController, the review prompt, code redemption) do not exist on the watch and are intentionally out of scope.

Implemented:

  • ✅ isAvailable — SKPaymentQueue canMakePayments.
  • ✅ queryProductDetails — product lookup via SKProductsRequest.
  • ✅ Purchase flow — buyConsumable / buyNonConsumable, purchaseStream, completePurchase, restorePurchases via SKPaymentQueue (a transaction observer whose updates are drained into purchaseStream).

Out of scope (no watchOS equivalent): the StoreKit UI surfaces (SKStoreProductViewController, the review prompt, code redemption).

Verified end to end against real StoreKit on a watch simulator, using the bundled watchos/Configuration.storekit test configuration: product lookup returns all four test products with prices, and a purchase completes (buy → purchaseStream reports purchased with a receipt → completePurchase finishes the transaction). Also builds and links on a physical Apple Watch (all 10 FFI symbols present in the device binary).

StoreKit testing only activates when the app is launched from Xcode — the scheme's StoreKit configuration is what turns it on. A CLI launch (flutter-watchos drive) does not enable it, so product lookups return "not found" there; example/integration_test/ skips its product assertions in that case rather than failing. To exercise purchasing, open example/watchos/Runner.xcodeproj and Run.

Example

example/ is the upstream in_app_purchase example app (its demo UI and official integration_test/), ported to watchOS with a runner via flutter-watchos plugin port --include-example. Run it on a watch simulator:

cd example
flutter-watchos drive \
  --driver=test_driver/integration_test.dart \
  --target=integration_test/in_app_purchase_test.dart \
  -d <watch-sim>

The demo exercises the full purchasing flow. On a bare Simulator there are no StoreKit products, so product lookup returns "not found" and a purchase cannot complete — add a .storekit test configuration (or use a sandbox account) to exercise it end to end.

License

The FlutterWatch Authors under a BSD-3-Clause license. See LICENSE for the full text.

Libraries

in_app_purchase_watchos