Google also announced a declarative UI framework. It's in the early stages and is open source. Android is on 9.x but that framework will run on much older versions of Android.
Meanwhile iOS 12 might be on 85% of iOS devices but it wont ever see SwiftUI.
Vast majority of the people with iOS12 will update. Also, at least on the announcement page, there seems to be no mention of iOS13 required for running apps using SwiftUI. Up until Swift 5 the whole runtime library needed to be shipped with the app and it is quite possible that a SwiftUI library could be shipped and run on iOS12.
Edit: On Apple developer forums I've read that the library is annotated with iOS13 requirement.
Yeah, I agree that Apple should have added at least one version worth of backwards compatibility if they want to see quick adoption. I suppose one could hide the whole view in defines and lug two implementations but that is not much better than waiting for one year.
Sure, but my company (and I assume most) will maintain support for at least the last two major versions of iOS. We wont be able to be minimum iOS 13 until ~September 2020 at the earliest, probably not until early 2021.
I understand why, I just wish they could release this open source like Jetpack Compose. Would've been a great way to introduce SPM to Xcode and iOS as well.
Google also announced a declarative UI framework. It's in the early stages and is open source. Android is on 9.x but that framework will run on much older versions of Android.
Meanwhile iOS 12 might be on 85% of iOS devices but it wont ever see SwiftUI.