I'm working with iOS developers overseas. I'm not an iOS developer myself.

I currently have an iOS app posted and available in the app store.

I had some work done recently to make a few changes to the app and now my developers are telling me:

"We can't upload the app because it's not archiving since our current project version doesn't have the latest Swift version".

Is this a real problem?

Their solution to this is that a lot of new work needs to be done which will be very expensive, but I'm skeptical that this is even a real problem.

Shouldn't I be able to upload changes to an app without the app having the "latest Swift version"?