Xcode 11 Beta 3, build error “Unknown attribute 'State'”, “Use of undeclared type 'View'” etc

Question

I build an app with the 2nd beta of Xcode 11, using SwiftUI, and everything worked completely fine, but now, with the 3rd beta, the app isn\'t even build. I get errors like

Answer 1

Got same issue on Xcode 11.2. Found out that the reason was that somewhere in same module I declared protocol State {}. This breaks compiler without any reasonable errors.

Answer 2

Instead @main, please replace @UIApplicationMain. I've attached screenshots. https://prnt.sc/vimvwn

Answer 3

I was getting the same "Unknown attribute 'State'" issue in Beta 5. But I was doing "@state" and not "@State". Case matters. It's hard to notice because both ways are shown as purple.

Answer 4

This is from the Xcode 11 Beta 3 Release Notes.

Known Issues

• Xcode 11 doesn’t support working with SwiftUI in an iPad app brought to macOS. (41416222, 51201699)

I downloaded the Xcode 11 Beta 3 myself just to confirm the errors you mentioned, and I had the same issues when trying to build a SwiftUI project for Mac.

I would suggest going back to using Xcode Beta 2 if possible. Unfortunately, Apple doesn't provide download links to previous betas, so hopefully you have a Time Machine backup or Beta 2 still installed on your computer. Otherwise, you might be out of luck until the next beta is released.