QuickTime for Windows existed long before then, and Apple ported a bunch of the old Classic Mac Toolbox to Windows as part of that.
IIRC it was actually this Windows port of Toolbox that in some ways laid the foundation for Carbon - i.e. a port of the Toolbox API to what became Mac OS X.
"There are clever, hardworking, stupid, and lazy officers. Usually two characteristics are combined. Some are clever and hardworking; their place is the General Staff. The next ones are stupid and lazy; they make up 90 percent of every army and are suited to routine duties. Anyone who is both clever and lazy is qualified for the highest leadership duties, because he possesses the mental clarity and strength of nerve necessary for difficult decisions. One must beware of anyone who is both stupid and hardworking; he must not be entrusted with any responsibility because he will always only cause damage." -- Kurt von Hammerstein
Yes. I maintain some open source Mac apps in my spare time (and even develop new ones from time to time) using Objective-C. I've known and used this programming language for 20 years, and don't really see the point of investing in Swift given the way the Apple ecosystem has developed.