[m_ke]

But wasn't open source till the end of 2015 (https://developer.apple.com/swift/blog/?id=34)

Kotlin was open sourced around 2012 and people were using it in Android apps before Google officially started supporting it in 2016.

[6700417]

Kotlin announcement 2017/5/17: https://android-developers.googleblog.com/2017/05/android-an...

Swift open source 2015/12/3: https://developer.apple.com/swift/blog/?id=34

[lokedhs]

That was the official support from Google. Kotlin had been around for a long time before that. I used to write Android applications using it before Google officially supported it.