What programming language is Audacity in? In the Wicki for building it on the Mac it refers to Xcode. Does this mean it has been translated into Swift for the Mac? I was under the impression it was in C++, and I was also under the impression Xcode didn’t support C++. I am also interested in what it is in for Linux and Windows.
Blessings, Joe. 
Mostly C++
The full source code is here: GitHub - audacity/audacity: Audio Editor
Yes we use Xcode on macOS.
No it hasn’t been translated into Swift.
Xcode supports source code for the programming languages C, C++, Objective-C, Objective-C++, Java, AppleScript, Python, Ruby, ResEdit (Rez), and Swift, with a variety of programming models, including but not limited to Cocoa, Carbon, and Java (Xcode - Wikipedia).
Audacity uses the same source code on all platforms. Many cross-platform differences are handled by wxWidgets, and remaining differences handle by pre-processor commands for conditional compilation [for example: “#if defined(WXMAC)” ]