I do not understand why I have to upgrade the enter operating system just so Swift Ui preview can work on Xcode?<p>Any apple engineers that can shed some light on this?<p>https://stackoverflow.com/questions/56678354/xcode-11-beta-swift-ui-preview-not-showing
I would think it's because Xcode uses the implementation of SwiftUI present in the OS to render the preview, which is only present in Catalina and not in Mojave. I presume they didn't think it worth the effort to re-implement SwiftUI rendering within Xcode itself just to support the older OS.