If you want to call rust from Swift, it should be easy. I work with C libraries and it easy to interface with module maps. However, with objective C the interoperability is trivial. As long as you pay attention to retain cycles, you can hold reference and call objc methods directly. That said, please make sure your framework can be imported into Swift properly. As most of the users will be using Swift.
Yes, I've seen examples of calling Rust from Swift, and I do plan to support that. This particular thing is about calling macOS platform functions from Rust code. Projects either call Objective-C API's from native Rust code using the dynamic invocation mechanism (which I think is slow and code-bloaty but want to measure more carefully), or they use the "cc" crate to include Objective-C code (and then generally use C ABI calls from Rust code into that). I've never seen Rust code that compiles Swift from a "cargo build" but of course would love to be proven wrong.
