swift-bridge

Call Rust from Swift and vice versa.

swift-bridge generates code that helps you call Swift from Rust and vice versa.

swift-bridge takes inspiration from the bridge module idea pioneered by cxx.

Current Status

swift-bridge is not yet production ready.

We need to use it more before we can be confident enough in the generated FFI glue to call swift-bridge production ready.

Right now I'm looking for feedback in order to continue to improve the APIs and the generated code.

I can especially use feedback from people with Swift experience, since I don't have much.

Installation

```toml

In your Cargo.toml

[build-dependencies] swift-bridge-build = "0.1"

[dependencies] swift-bridge = "0.1" ```

Quick Peek

Here's a quick peek at how bindings look.

A more thorough walk through of swift-bridge can be found in the book (TODO: Link to GitHub pages).

```rust // lib.rs

[swift_bridge::bridge]

mod ffi { // Shared types #[swiftbridge(swiftrepr = "struct")] struct ASharedStruct { field: u32 }

// Exposes super::ARustStack to Swift.
extern "Rust" {
    type ARustStack;

    fn push (&mut self, val: u8);

    fn pop (&mut self) -> Option<u8>;

    fn as_slice (&self) -> &[u8];

    fn do_stuff(override: Option<u8>);
}

// Exposes a Swift class to Rust.
extern "Swift" {
    type SwiftApiClient;

    #[swift_bridge(init)]
    fn new_with_timeout(timeout: u8) -> SwiftApiClient;

    #[swift_bridge(associated_to = FileSystemClient)]
    fn version () -> String;

    fn post_bytes(&self, bytes: &[u8]);
}

} ```

TODO's before open sourcing

Create a tutorial on setting up a project

Built-In Types

swift_bridge comes with support for a number of Rust and Swift standard library types.

| name in Rust | name in Swift | notes | | --- | --- | --- | | u8, i8, u16, i16... etc | UInt8, Int8, UInt16, Int16 ... etc | | | bool | Bool | | | String, &String, &mut String | RustString | | | &str | RustStr | | | Vec | RustVec\ | | | SwiftArray\ | Array\ | Not yet implemented | | &[T] | UnsafeBufferPointer\ | | | &mut [T] | UnsafeMutableBufferPointer\ | Not yet implemented | | SwiftString | String | | | Box | | Not yet implemented | | [T; N] | | Not yet implemented | | *const T | UnsafePointer\ | | | *mut T | UnsafeMutablePointer\ | | | Option\ | Optional\ | Currently only supports function return types that are primitive (i.e. -> Option<i32>), or -> Option<String>..
More support will come.
Other places such as function arguments are not yet implemented but will come.
| | Result\ | | Not yet implemented | | Have a Rust standard library type in mind?
Open an issue! | | | | | Have a Swift standard library type in mind?
Open an issue! | |

To Test

To run the test suite.

```sh

Clone the repository

git clone git@github.com:chinedufn/swift-bridge.git cd swift-bridge

Run tests

cargo test --all && ./test-integration.sh ```