AndroidAppRuntime

The Android host for AppRuntime apps. An AppRuntime app is guest code only: a universal bundle with App.wasm and native libapp.a slices. This repository will turn one into an Android app:

• the host runtime, in Swift: the Activity shell, the main looper, the runtime core behind rt.h, and the contract implementations over the Android SDK. Each contract module is Swift over a small Kotlin class, bound with swift-java; Motion reads the NDK's sensors directly;
• the SwiftUI player: AndroidSwiftUI's Compose interpreter, behind an adapter for AppRuntime's render IR;
• the packager, android-app, which turns a universal bundle into a signed APK or App Bundle.

Status: phase 3 of the plan: every AppRuntime contract module runs on Android, checked on the emulator by Scripts/contracts-check.sh. In phase 2, android-app packages a universal bundle as a debug APK, or as a signed release APK or App Bundle. Before that, in phase 1: AppRuntime's ExampleUI runs from its universal bundle in the emulator, rendered by AndroidSwiftUI's composeui. Taps, typing, the lazy list, navigation and the back gesture all reach the guest and come back.

Phase 0 ran AppRuntime's ExampleApp from its sealed Android slice, with every check of AppRuntime's linked-slice test passing.

It is the counterpart of DarwinAppRuntime and LinuxAppRuntime.

Building

Swift 6.4 is required (.swift-version pins 6.4.2), with the Swift SDK for Android set up with NDK r30. Its runtime needs r30's libc++_shared.so, although its setup script accepts r27:

swift sdk install https://download.swift.org/swift-6.4.2-release/android-sdk/swift-6.4.2-RELEASE/swift-6.4.2-RELEASE_android.artifactbundle.tar.gz \
    --checksum 4d6ad63ea74becd58e123ff58b1b48c3be5ec0db0dff0ea5abe37ac007dd3233
ANDROID_NDK_HOME=~/Library/Android/sdk/ndk/30.0.16248370 \
    ~/Library/org.swift.swiftpm/swift-sdks/swift-6.4.2-RELEASE_android.artifactbundle/swift-android/scripts/setup-android-sdk.sh

Then, with an emulator running and these checkouts next to this one:

• AppRuntime, with its RuntimeHost module (or APPRUNTIME_PATH);
• AndroidSwiftUI, for composeui (or ANDROIDSWIFTUI_PATH).

Scripts/example-ui.sh --run

The script:

• builds ExampleUI's universal bundle with AppRuntime's guest.py;
• links its slice into libapp.so with the host;
• builds Android/example-ui with Gradle, on a JDK from 17 to 21;
• installs it, and drives it with UI Automator (Scripts/example-ui-check.py).

It uses a running emulator unless ANDROID_SERIAL names a device. Scripts/example-app.sh --run does the same for phase 0.

Contracts

The host implements AppRuntime's contract modules: Device, Formatting, Location, Networking, Bluetooth (the central role), Motion and NFC (the reader role), and the Permissions built-in over Android's runtime permissions.

Scripts/contracts-check.sh

The script builds Examples/ContractsCheck, a guest app that calls every contract and shows one ok or FAIL line per check, and packages it with android-app run. Scripts/contracts-check.py then reads the lines from the player's trace in logcat, and makes things happen for the app to see:

• it changes the emulator's battery and GPS position;
• it answers the location, Nearby devices and physical activity prompts.

Networking's checks need the Internet (httpbin.org). Bluetooth scans, and connects to the first connectable device it finds, if any. NFC needs a device with NFC; on the emulator, the check confirms the session fails as it should.

Packaging

android-app turns a universal bundle from AppRuntime's guest.py bundle into an Android app:

swift run android-app validate App.app

swift run android-app run App.app

ANDROID_KEYSTORE_PASSWORD=… swift run android-app package App.app --aab --keystore release.jks --alias release

• validate checks the app against this host: its keys, its contracts and its slices.
• run builds a debug APK, installs it on a running emulator (or --device), and starts it.
• package builds a debug APK, or a signed release with --release or --aab. Release passwords come from ANDROID_KEYSTORE_PASSWORD and ANDROID_KEY_PASSWORD.
• gradle writes the app's Gradle project, for Android Studio.

Each ABI the bundle has is built, unless --abi picks some. The work goes in .build/android-app/<identifier>/.

Tests

swift test runs the host's and the packager's unit tests on macOS. Run the player's tests from Android/:

./gradlew :appruntime-ui:desktopTest