In iOS 12 and 13, up to 13.4, few lines of codes:navigationController?.navigationBar.isTranslucent = falsenavigationController?.navigationBar.barTintColor = .blacknavigationController?.navigationBar.tintColor = .redallow to hide the status bar under the navigation bar.With swiftUI is perhaps even simpler.statusBar(hidden: hideStatusBar)but it requires to rewrite the whole app from storyboard to swiftUI.Hiding the status bar, or go to full screen, is still be possible without using swiftUI on legacy code?

Studing SwiftUI in Apple's HandlingUserInput, I'm blocked in this error:No ObservableObject of type UserData found. A View.environmentObject(_:) for UserData may be missing as an ancestor of this view.The code is:final class UserData: ObservableObject { @Published var showFavoritesOnly = false @Published var landmarks = landmarkData }struct LandmarkList: View { @EnvironmentObject var userData: UserData var body: some View { NavigationView { List(landmarkData) { landmark in if !self.userData.showFavoritesOnly || landmark.isFavorite { NavigationLink(destination: LandmarkDetail(landmark: landmark)) { LandmarkRow(landmark: landmark) } } } .navigationBarTitle(Text("Landmarks")) } } } struct LandmarkList_Previews: PreviewProvider { static var previews: some View { LandmarkList() .environmentObject(UserData()) } }".environmentObject(UserData())" is present in the preview."@EnvironmentObject var userData: UserData" in the View.But the use of userData (if !self.userData.showFavoritesOnly) cause the fatal error.Can someone help me in undertanding how to proceed?

I would add a template image at a button to change its color runtime.I used Preview to draw and save it as a pdf.But it is rendered only as a uniform square color (which color I can change runtimne).How can I obtain the template pdf image?Why the pdf saved by Preview is not working?