Just a note creating an iOS Swift Single View App project in Xcode 11.5 (11E608c)
Mac OS 10.15.2
Don’t call your app SwiftUI.
If you create an iOS Single View project and name your app something like Sample, the app will be able to build and preview.
If you misguidedly yet well meaningly name your app SwiftUI, you’ll get these errors after creating the app.