The course she bought (without my input btw, she's pretty independent!) uses Swift. And that's probably right. Swift is a much nicer language than Objective-C, much closer to modern languages and has far less of the C heritage poking through. Even with the deprecation warnings, it's probably easier to deal with.

Removing x++ is indeed minor, which is why it's so curious. Sure, there are arguments for removing it. But there are also arguments for minimising language churn and just living with these things.

You could give a little help to your girlfriend. How about installing for her the required swift version by her course with swiftenv? This way she could learn the basics without getting nagged by Xcode. Later she could read up the differences and port her code to practice.

Living with x++ wouldn't be terrible, but I don't mind having to make changes to my code now that Swift is still very new if it ends up becoming a better language. Teaching x++ and ++x to beginners can be quite a pain.

It feels backward to modify the language in a way that makes it less functional: replacing a construct that returns a value with one that returns Void.

Definitely going against the general language trend, there.

And the justifications to remove ++ are downright bizarre in my opinion.