Java can, but Swift cannot, mostly due to issues of how to bridge C++ concepts such as templates, assignment semantics, etc. to the type system.

Without native bindings, you'd still need to write all the UI code in C, and then you could use Swift interop to call your C function that does the layout. That's not what most would think of as Swift support if you're writing C.

Yes, but not C++ code. Also, many environments, such as Linux, don't support the Objective-C runtime at all.

Swift call C++ code with Bridge

Java call C++ code with JNI

You can get more details here:

https://github.com/idea4good/GuiLitesamples