Purely from the standpoint of making GUI apps in macOS/iOS, Swift is almost certainly the best choice. All of Apple’s UI frameworks are written in Swift (technically often Objective-C, but with Swift in mind), and designed to be used from Swift. It’s kind of possible to do this in C++ using Objective-C++, but nearly all of the UI code is going to be Objective-C anyways (Objective-C is the language that used to be the default on Apple platforms, but was replaced by Swift). It’s also certainly possible to use libraries for other languages that wrap this functionality, but these often can be missing features and/or be harder to work with. Additionally when looking for help, you’re likely to find much more support out there for the native frameworks since that’s what most people are using.

OK - well at the end of the day the right approach is to have a problem you're trying to achieve and pick the best language for that (wether you know the language or not).

If it's MacOS/iOS apps, then definitely don't choose Rust. But reconsider that choice for your next project.

Also, with modern large language models, it's even easier to work with an unfamiliar language. And honestly it wasn't ever all that difficult.