Surprised noone mentions Kotlin. It's quite Swift-like, backed by JetBrains (Android Studio is based on their IntelliJ Idea), and 1.0 has only just been released. It has full interoperability with Java.

Given the above, I don't see much point in using Swift, unless it's one of these projects that are about proving a point (nothing wrong with that and often very interesting).

I love Kotlin, but being able to develop libraries in one language and use them in both Android and iOS is huge. I have been using J2Objc for this until now, and while it's a great tool, it forces me to use Java, which I don't love. I would prefer being able to use Kotlin on iOS, but using Swift for Android development is a great boon.

Could you develop libraries that way, though? It would have to be absolutely pure Swift, not using any iOS libraries, like NSURL etc. etc. - surely incredibly limiting.

Not true. Both Foundation and Core Foundation libraries will be eventually ported and open sourced.

This feels a little like wishful thinking. Remember YellowBox back when Apple originally bought NeXT?

YellowBox was going to be a cross-platform updated version of the OpenStep APIs. While I remember some alphas of it, it basically got nixed.

http://www.roughlydrafted.com/RD/RDM.Tech.Q1.07/4B800F78-0F7...

As much as I enjoy using Apple products, their history says that they would not directly support something like this.

https://github.com/apple/swift-corelibs-foundation https://github.com/apple/swift-corelibs-libdispatch

Works is well under way.