Hi, from what I understand syntax highlighting is defined by built-in syntax types in Built-in Syntax Types.xcsynspec, with language-specific identifiers each in their own .xclangspec file. This gives room for customization beyond adjusting dvtcolortheme settings.
However, is it possible to get the syntax identifier parsed by Xcode in any way? For Swift one can derive syntax identifiers with SourceKit-LSP, but it's not possible for Objective-C, because SourceKit-LSP interfaces sourcekitd for Swift, but clangd for Objective-C.