All the solutions from this thread did not work for me when the application was in production. It only works during the development process. More over, I am not sure that adding the UIView.appearance(whenContainedInInstancesOf:) call within the @main app entry initializer is a good practice as swiftUI views call it every time the view redraws. The trick for me was calling appearance without the parameter whenContainedInInstancesOf of appearance(), on a onAppear() modifier. It also work only when setting the color this way: UIColor(named: "AccentColor"). Calling UIColor(.accentColor)from SwiftUIColor` does not work. @main struct AwesomeApp: App { var body: some Scene { WindowGroup { Group { ContentView() } .onAppear { UIView.appearance().tintColor = UIColor(named: "AccentColor") } } } }

It seems that on my side, the startAccessingSecurityScopedResource() method throws an error and can not access the user Privacy settings. When looking in the iPhone Settings -> Privacy -> Files and Folders, my application doesn't appear and it seems that it has no access to this part of iOS. Have you been able to solve your question since?

I have found a way to set the system background color using SwiftUI. It is pretty handy when you want the background color in dark mode of the modal view..foregroundColor(Color(UIColor.systemBackground))

Have you tried any setup in your application scheme settings under Test? You must change it to add the .xctestplan file.