Kotlin is about as nice as Swift until you run into some bit where it's interfacing with Java and then it becomes a lot less fun. Swift I think handles Obj-C/C

Kotlin is about as nice as Swift until you run into some bit where it's interfacing with Java and then it becomes a lot less fun. Swift I think handles Obj-C/C interior a bit more gracefully by comparison. Various bits of other JVM baggage also aren't great. That said I've only used Kotlin in the context of Android development. It might be nicer elsewhere.