How to detect if the SwiftUI application in background or foreground

demoApp.swift

import SwiftUI

@main
struct ios14_demoApp: App {
    @Environment(\.scenePhase) var scenePhase
    
    var body: some Scene {
        WindowGroup {
            ContentView()
        }.onChange(of: scenePhase) { phase in
            switch phase {
            case .background:
                print("App is in background")
            case .active:
                print("App is Active")
            case .inactive:
                print("App is Inactive")
            @unknown default:
                print("New App state not yet introduced")
            }
        }
    }
}