Rust Catalyst Example

This is an example that shows how to build a static library supporting Mac Catalyst (X86_64 and ARM64) from Rust.

Usage

Until this PR that adds Catalyst ARM64 support to Rust is merged, you need to build the Rust compiler. Hence, jump to the end to see how to build and use a custom Rust toolchain based on 77484.

This repo contains an Xcode project that sets up everything to include a library written in Rust and call functions in it. The repo is set up to use ARM64 and X86_64 Catalyst. It should compile fine if you select the My Mac target. If you select the Any Mac target, it requires the above mentioned PR / a custom toolchain.

The Xcode project also contains all the required binaries to try this out immediately. You can just open XcodeIntegration.xcodeproj and build.

Usage with normal nightly Rust

Requirements

1. Rustup / Rust Nightly
2. Xcode 12

Full Local Installation

rustup toolchain install nightly
rustup toolchain default nightly
rustup target add aarch64-apple-ios
rustup target add x86_64-apple-ios

# Or use a directory override
rustup override set nightly

./make_fat.sh

It will automatically generate the binaries and write them to XcodeIntegration/Rust

Open Xcode, hit compile.

build-std

Catalyst is not a tier 1 Rust platform, so there is no pre-build standard library. This repository uses cargo build-std to automatically build the standard library for the given platform. This takes a bit longer but works reliably (at least for me).

Custom Rust Toolchain

git clone https://github.com/rust-lang/rust.git
cd rust
cp config.toml.sample config.toml

Edit config.toml and change build-stage = 1 to build-stage = 2 (line 149)

./x.py build 

Install with

rustup toolchain link myrust ~/rust/build/x86_64-apple-darwin/stage2/

Go back to this directory

rustup default myrust

Now you can continue with (Full Local Installation) above.