RestSend Client SDK

RestSend is a secure instant-messaging platform (server in Go, client SDK in Rust) that targets Android, iOS, Flutter, WASM, and desktop. The Rust core exposes a high-reliability protocol, sync callbacks, and full OpenAPI/Webhook support so that existing user systems can extend or embed the service with minimal effort.

• Benchmarked with 80%+ unit-test coverage and millions of concurrent connections per node.
• SDK crates live in crates/ and power mobile bindings (android-sdk, swift/) plus WebAssembly (crates/restsend-wasm).
• A Flutter/Dart package is shipped under dart/restsend_dart for cross-platform UI apps.

Try the online demo or reach out at kui@fourz.cn.

Requirements

• Rust 1.85+ (rustup update if needed) and basic build dependencies (clang, cmake).
• Optional: rsproxy.cn mirrors for faster builds inside China.
• Platform extras:
  • iOS/macOS: rustup target add aarch64-apple-ios aarch64-apple-ios-sim x86_64-apple-darwin and Xcode 15+.
  • Android: Android NDK r25c+, set NDK_HOME, install cargo-ndk, and add aarch64-linux-android, armv7-linux-androideabi, x86_64-linux-android targets.
  • Flutter/Dart: Flutter 3.24+, Dart 3.5+, flutter_rust_bridge_codegen 2.11.1.
  • WASM: Node.js 20+, wasm-pack, wasm-bindgen-cli, wasm-opt from Binaryen.

Quick Start

git clone https://github.com/restsend/restsend-rs.git
cd restsend-rs
cargo test                     # verify the Rust core

Choose a target build from the sections below.

iOS / macOS Swift SDK

1. Add the pod inside your Xcode project:

   pod 'restsendSdk', :path => '../restsend-rs'

2. Build the Rust library for simulator/device:

   cargo build --release --target aarch64-apple-ios-sim --target aarch64-apple-ios --target x86_64-apple-darwin

3. Regenerate Swift bindings when the API changes:

   cargo run --release --bin bindgen -- --language swift [-p true]   # add -p true to publish the pod bundle

Android / Kotlin SDK

export NDK_HOME=/path/to/android-ndk-r25c
cargo ndk -t arm64-v8a -t armeabi-v7a build --release
cargo run --release --bin bindgen -- --language kotlin
cargo ndk -t arm64-v8a -t armeabi-v7a -o ./jniLibs build --release   # copies .so into jniLibs/
cd android-sdk && ./gradlew assembleRelease

Add JNA (or your preferred loader) plus network/storage permissions in your Android app manifest when embedding the produced AAR.

Flutter / Dart bindings

The package under dart/restsend_dart uses flutter_rust_bridge.

dart run build.dart   # runs all required steps from the repo root

The helper script installs/updates flutter_rust_bridge_codegen, installs Dart deps, runs build_runner, regenerates bindings, and finally builds the restsend-dart crate.

Run flutter run from dart/restsend_dart/example to try the demo UI.

WebAssembly package

cargo install wasm-pack wasm-bindgen-cli
cd crates/restsend-wasm
npm install --force
npx playwright install webkit
npm run build

Ship the generated artifacts from crates/restsend-wasm/pkg/ (plus assets/) in your web app.

Testing & Demos

• cargo test exercises the core logic.
• cargo run -p demo launches the native desktop sample (requires GUI environment).
• dart/restsend_dart/example showcases the Flutter bindings end to end.

Need help or commercial support? Email kui@fourz.cn.