My team and I ran a rather complex backend application written in Swift for several years in production.

There are nice things about the language, but so many things are missing, poorly supported or just extremely annoying.

A teammate wrote a summary of the myriad issues we had: https://forums.swift.org/t/issues-learned-4-years-with-serve... I could probably add a half dozen more things.

I am now working with Kotlin and it's such a delight in comparison.