SwiftUI—如何在预览窗口使用不同的模拟器预览用户界面

struct ContentView : View {
    var body: some View {
        VStack{
            Text("Dynamic Type sizes")
                .font(.system(size: 48))
            Text("Dynamic Type sizes")
        }        
    }
}
#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        Group {
           ContentView()
              .previewDevice(PreviewDevice(rawValue: "iPhone 8"))
              .previewDisplayName("Device-8")
           ContentView()
              .previewDevice(PreviewDevice(rawValue: "iPhone XS Max"))
              .previewDisplayName("Device-XS Max")
        }
    }
}
#endif