Xcode 11 beta 5 SwiftUI changes

NavigationButton  becomes  NavigationLink  Select all

NavigationButton( destination: LandmarkDetail(landmark: landmark)) { LandmarkRow(landmark: landmark) }

NavigationButton  becomes  NavigationLink  Select all

NavigationLink( destination: LandmarkDetail(landmark: landmark) .environmentObject(self.userData) ) { LandmarkRow(landmark: landmark) }

ForEach  .identified by:  Select all

ForEach(["iPhone SE", "iPhone XS Max"].identified(by: \.self)) { deviceName in LandmarkList() .previewDevice(PreviewDevice(rawValue: deviceName)) .previewDisplayName(deviceName) } .environmentObject(UserData())

ForEach  id:  Select all

ForEach(["iPhone SE", "iPhone XS Max"], id: \.self) { deviceName in LandmarkList() .previewDevice(PreviewDevice(rawValue: deviceName)) .previewDisplayName(deviceName) } .environmentObject(UserData())

BindableObject  becomes  ObservableObject  Select all

final class UserData: BindableObject { let didChange = PassthroughSubject<UserData, Never>() var showFavoritesOnly = false { didSet { didChange.send(self) } } var landmarks = landmarkData { didSet { didChange.send(self) } } }

BindableObject  becomes  ObservableObject  Select all

final class UserData: ObservableObject { @Published var showFavoritesOnly = false @Published var landmarks = landmarkData }

How to use SwiftUI previews for existing project and storyboard

Here is an example code to create a new swift file for an existing project and use the storyboard Main.storyboard and preview the MainViewController instance in the new iOS 13 SwiftUI framework under Xcode 11.

If you add TabbedView to NavigationView in this example, please use Xcode 11 Beta 2.

MainViewPreviews.swift    Select all

// MainViewPreviews.swift // FishTagCreator // // Created by javacom on 8 Jun 2019. // import SwiftUI #if DEBUG struct MainViewControllerPreviews : PreviewProvider, UIViewControllerRepresentable { // MARK: PreviewProvider static var previews: some View { MainViewControllerPreviews() } // MARK: UIViewControllerRepresentable typealias UIViewControllerType = MainViewController func makeUIViewController( context: Context ) -> MainViewController { let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil) let mainViewController: MainViewController = mainStoryboard.instantiateViewController(withIdentifier: "MainController") as! MainViewController return mainViewController } func updateUIViewController( _ uiViewController : MainViewController, context: Context) { } } #endif

It is important to assign a storyboard ID say "MainController" to your MainViewController in Main.storyboard's identity inspector.