Is SwiftUI backwards-compatible with iOS 12.x and older?

Question

If I have an app made with SwiftUI, will it work for iOS below iOS 13?

Answer 1

If you are shooting to support iPhone and not iPad you could probably expect most users will upgrade to iOS 13 within 12-18 months(starting with the release date). Maybe 85-90%? (I think Apple said at this point theres still 15% of people not on iOS 12) That’s still quite a while though to where you aren’t going to be able to deploy SwiftUI apps right away or else risk alienating a lot of users.

Also depending on what the other 10-15% is, that could mean a lot of users (and $$) for you left on the table.

If you are supporting iPad as well then its more tricky because people don't upgrade their iPads as often. Theres a lot of iPad 2s along with 3rd and 4th generation iPads still out in the wild, that only have 10.3.3 and cannot upgrade anymore. People just aren't going to go get up and go pay between $400 - $1,000 for a new iPad when theirs works perfectly fine.

There’s always room and a need for updating the app, making it better, fixing bugs, that don’t necessarily have anything to do with iOS 13. i.e. finding a bug you didn’t know about before that making a lot of users unhappy.. not on the latest iOS version. and we haven't even talking about enterprise / corporate customers that a lot of dev shops support. theres a lot of more pushback on iOS updates for various reasons in that area.

So before you get all excited about iOS 13 and SwiftUI (which you absolutely should because its awesome), back in the real world, outside of Silicon Valley, that's not exactly going to align with what the average consumer expects and you will need to support older devices and need to because theres just too many people you would be alienating.