example-rust-bindings

The minimal code I could write to get code written in Rust to execute in:

• Web (by compiling to WASM)
• Android (by compiling to native)
• TODO iOS (by compiling to native)

For more explanation see Building cross-platform Rust for Web, Android and iOS – a minimal example.

Prerequisites

You will need to set up quite a few things - please read the Prerequisites section in each of the READMEs:

• bindings/wasm/README.md
• bindings/ffi/README.md

The short answer is that you will need: Rust, NodeJS, npm, wasm-pack, Android NDK and the Cargo config to use it, Rust targets for all Android platforms, uniffi-bindgen. For iOS you will need to be running under OS X, with xcodebuild and lipo as well as the Rust targets for the iOS platforms.

Building the bindings

To build all the bindings, try:

make

Or if you're not on OS X:

make web android

Alternatively, to build for a single platform, or to learn more, see the individual README files:

• Web: bindings/wasm/README.md

• Android & iOS: bindings/ffi/README.md

How it works

crates/example-rust-bindings contains our normal Rust code.

bindings/ffi contains code and config to build shared object files for various types of Android, and for iOS. It uses uniffi-bindgen to generate the required extra code. bindings/ffs/src/build.rs runs the uniffi command to generate the "scaffolding", and bindings/ffi/src/my_rust_code.udl contains the definition of the code we want to share between platforms.

bindings/wasm contains code and config to build .js and .wasm files meaning we can use our Rust code in JavaScript for the Web. It does not use uniffi - instead it is based on wasm_bindgen and requires nodejs to build.

examples/example-android contains an Android project that uses our Rust code. examples/example-android/app/build.gradle contains a android.applicationVariants.all section that uses bindings/ffi/src/my_rust_code.udl to generate Kotlin code. Our normal Kotlin code can use the Rust by calling functions inside the uniffi.my_rust_code namespace.

examples/example-web contains an example of how to use our Rust code in a web page. examples/example-web/index.html loads the WASM in a module and calls functions inside it.

examples/example-ios contains an example of how to use our Rust code in iOS. Most of its contents are actually generated when we run the build for bindings/ffi.

License

Apache-2.0