# swift-bridge [](https://github.com/chinedufn/swift-bridge/actions) [](https://docs.rs/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](https://github.com/dtolnay/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
#[swift_bridge(swift_repr = "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<T> | RustVec\<T> | |
| SwiftArray\<T> | Array\<T> | Not yet implemented |
| &[T] | UnsafeBufferPointer\<T> | |
| &mut [T] | UnsafeMutableBufferPointer\<T> | Not yet implemented |
| SwiftString | String | |
| Box<T> | | Not yet implemented |
| [T; N] | | Not yet implemented |
| *const T | UnsafePointer\<T> | |
| *mut T | UnsafeMutablePointer\<T> | |
| Option\<T> | Optional\<T> | Currently only supports function return types that are primitive (i.e. `-> Option<i32>`), or `-> Option<String>`..<br /> More support will come.<br /> Other places such as function arguments are not yet implemented but will come.<br /> |
| Result\<T> | | Not yet implemented |
| Have a Rust standard library type in mind?<br /> Open an issue! | | |
| | Have a Swift standard library type in mind?<br /> 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
```
## See Also
- [Rust on iOS](https://mozilla.github.io/firefox-browser-architecture/experiments/2017-09-06-rust-on-ios.html)
- A blog post by Mozilla that explains how to run Rust on iOS.