Try `rustup target add aarch64-apple-ios` and see how far you get. It&#x27;s a tier 2 platform so it usually has builds available. But the iOS targets are some of the least tested for Rust. I have no idea if they work!<p>The process for adding tier 2 platforms isn&#x27;t well defined but is closely related to ease of automation. If it can be done in a Docker container then it is simple to build std and ship it. Right now we&#x27;re enthusiastic about this level of support - we can provide builds of std for lots of things. As long as somebody cares just enough to keep std building, which is pretty easy to do.<p>Whether those builds work at all is a different matter! We don&#x27;t run tests on most tier 2 platforms. It&#x27;s a big commitment to do so, even more to keep the tree green.<p>Personally, I really want to say that in time Rust will have perfect test and build automation on all platforms that matter even a little bit. All platforms are on a slow treadmill to perfection. They all come with maintenance burden, but the more successful the project is the more maintenance (and perfection) we can afford. Hm, I hope that&#x27;s how it works...