Swift will be more prevalent than Crystal. There are already some serious frameworks available and you get the additional bonus of being able to write Mac and iOS with the language as wel.
The server-side swift ecosystem is incredibly small, and that's by far the most important thing for adoption.
You're not really going to share backend source with your iOS apps, so there's nothing to really gain there. Languages are so homogenized these days that moving between the popular few is pretty simple and requires fairly minimal rampup.
You're not really going to share backend source with your iOS apps, so there's nothing to really gain there. Languages are so homogenized these days that moving between the popular few is pretty simple and requires fairly minimal rampup.