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

Sadly no, SwiftUI is only allowed in iOS 13 and above. It was introduced in the iOS 13 framework. Before iOS 13, everything was built using Obj-C framework (Including Swift).

On the right side of the dev documentation, it shows the supported versions of iOS, macOS, tvOS, watchOS, etc.

https://developer.apple.com/documentation/swiftui/

Hope this helps!