This is a follow up PR for #7166 adds @objc annotations to Swift catalogMetadata() methods, because the Swift 4 compiler no longer attempts to infer what methods should be visible to Objective-C. As a result of this change in the compiler, no Swift examples were showing up in Dragons after #7166. See this article: https://useyourloaf.com/blog/objc-warnings-upgrading-to-swift-4/ for additional context.