If I upgrade my iOS app target from iOS 11 to iOS 13, what happens to pre-13 users?

Question

I have an app on the App Store which targets iOS 11.

I would like to use SwiftUI for a new version of my app, so I need to change the target to iOS 13. But, won't this alienate pre-iOS 13 users??

Will the App Store provide access (update or first install) to the earlier version for users who are not yet on iOS 13? Or will they forced to upgrade or blocked from using the app?

If it's possible to support both pre-iOS 13 and iOS 13 users, what do I need to do or is it automatic?

Answer 1

People who already have the app installed will keep the old version; the update won't be available.

Additionally, if you make the old version available under "last compatible version" in App Store Connect, those users will be able to re-install that old version if they remove it or install it on an additional device.

Anyone that has not already purchased the app will need at least iOS 13 to be able to install it.