&gt;but being able to develop libraries in one language and use them in both Android and iOS is huge<p>I have no doubt that there are mobile only apps that would find this valuable - but swift is still <i>only</i> linux&#x2F;android and osx&#x2F;ios - if you want truly portable code - that can compile to browser&#x2F;mobile&#x2F;server&#x2F;desktop you&#x27;re stuck with C++ for the foreseeable future.