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

swift macos swiftui xcode11 uikitformac
Shahar picture Shahar · Jul 10, 2019 · Viewed 12.1k times · Source

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 "Use of undeclared type 'View'", "Unknown attribute 'State'" etc. What can I do? Is the problem in my code or is it just a bug?

The problem is when I'm trying to build the app to run on my Mac (with UIKit for Mac)

@State var score = 0

The error is "Unknown attribute 'State'"

struct ContentView : View {
    /*...*/
}

The error is "Use of undeclared type 'View'"

Answer

oroom picture oroom · Nov 27, 2019

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.

Related questions

How to open file dialog with SwiftUI on platform "UIKit for Mac"?

NSOpenPanel is not available on platform "UIKit for Mac": https://developer.apple.com/documentation/appkit/nsopenpanel If Apple doesn't provide a built-in way, I guess someone will create a library based on SwiftUI and FileManager that shows the dialog to …

Read More
Check OS version in Swift?

I'm trying to check system information in Swift. I figured out, that it could be achieved by code: var sysData:CMutablePointer<utsname> = nil let retVal:CInt = uname(sysData) I have two problems with this code: What should be …

Read More
How to remove all subviews of a view in Swift?

I'm looking for a simple method to remove at once all subviews from a superview instead of removing them one by one. //I'm trying something like this, but is not working let theSubviews : Array = container_view.subviews for (view : NSView) …

Read More