Well, the documentation for Objective-C/C++ has mostly been removed. It's all Swift based how-tos, videos and learning material. You have to hunt Google for getting anything. You get better material for Objective-C/C++ on the LLVM home page. Most of the old Objective-C links are dead.
Perhaps I should have said feature frozen on-the-way to deprecation instead. All new development in lang/ux is happening in Swift/SwiftUI.