The file templates for XCode 6.1 (which is what I used for this release) are located in
▸ Applications ▸ Xcode ▸ Contents ▸ Developer ▸ Library ▸ Xcode ▸ Templates ▸ File Templates ▸ Source
Copy the Rust File.xctemplate folder in there and restart XCode. You should now be able to create new Rust files from the template.
