I certainly agree with you for using platform-specific languages for platform-specific features. But I much prefer to write the main logic of an app in C++ and

I certainly agree with you for using platform-specific languages for platform-specific features. But I much prefer to write the main logic of an app in C++ and use Swift as the glue to the UI rather than use Swift for everything. I'm not yet sold on Swift, and being unable to take the code to other platforms is also a strike against it, for now.