If you want to go mobile, then golang is obviously out. If you choose between iOS and Android, then I suggest to start with iOS first. It's much easier to learn

If you want to go mobile, then golang is obviously out. If you choose between iOS and Android, then I suggest to start with iOS first. It's much easier to learn because it's not fragmented and thus results in a simpler platform API. This said, go with Swift for iOS. It's great and also very similar to Kotlin. I have programmed years with both besides many other languages. I however believe that platform independent programming tools such as React Native will become more important in the future. Still it helps a lot knowing native programming itself. I personally enjoy developing for devices the users can touch. If that's the case for you, too, get involved with iOS programming next.