For iOS you can still use Objective C, but there are additions to platform frameworks and whole new frameworks that are Swift first. I don’t really know how hard it would be to use those APIs from Objective C. Swift is certainly the default going forward.
I don’t work on Android but my understanding is that Java hasn’t and isn’t going anywhere on Android. Kotlin is supposed to be great but I haven’t heard mention of Java being dropped.
For iOS you can still use Objective C, but there are additions to platform frameworks and whole new frameworks that are Swift first. I don’t really know how hard it would be to use those APIs from Objective C. Swift is certainly the default going forward.
I don’t work on Android but my understanding is that Java hasn’t and isn’t going anywhere on Android. Kotlin is supposed to be great but I haven’t heard mention of Java being dropped.
Not dropped, but google has suggested all new android projects be done with Kotlin instead