如何在iPad上更改SwiftUI拆分视图中的主控视图宽度

import SwiftUI

struct ContentView: View {
    @State private var displayMode: UISplitViewController.DisplayMode = .allVisible
    
    var body: some View {
        NavigationView {
            List(0..<10) { item in
                NavigationLink(destination: DetailView(item: item)) {
                    Text("Item \(item)")
                }
            }
            .navigationTitle("Main View")
            .listStyle(InsetGroupedListStyle())
        }
        .navigationViewStyle(StackNavigationViewStyle())
        .onAppear {
            if let splitViewController = UIApplication.shared.windows.first?.rootViewController as? UISplitViewController {
                splitViewController.preferredDisplayMode = displayMode
            }
        }
        .toolbar {
            ToolbarItem(placement: .navigationBarTrailing) {
                Button(action: {
                    switch displayMode {
                    case .allVisible:
                        displayMode = .primaryHidden
                    case .primaryHidden:
                        displayMode = .primaryOverlay
                    case .primaryOverlay:
                        displayMode = .automatic
                    default:
                        displayMode = .allVisible
                    }
                    
                    if let splitViewController = UIApplication.shared.windows.first?.rootViewController as? UISplitViewController {
                        splitViewController.preferredDisplayMode = displayMode
                    }
                }) {
                    Image(systemName: "arrowtriangle.down.fill")
                }
            }
        }
    }
}

struct DetailView: View {
    let item: Int
    
    var body: some View {
        Text("Detail for Item \(item)")
            .navigationTitle("Detail")
    }
}

@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}