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.
