Is that even possible?
I made an archive, validated & pushed it to itunes connect and I got a mail saying:
Invalid Deployment Target - Apps built with Swift must have a Deployment Target of 7.0 or later.
I get that swift is not supported on iOS 6 but since extensions are not either, doing this should be possible no?
The containing app itself is still entirely written in Objective-C.
I'm aware that extensions are available only on iOS 8.