SwiftUI_NotificationCenter fore and back

gistfile1.txt

import SwiftUI

struct ContentView: View {
    
    @State var model =  OrientationModel()
    
    var body: some View {
        VStack {
        Text("Hello, World!")
        }
        .onAppear {
            self.model.contentView = self
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

final class OrientationModel: ObservableObject {
    
    var contentView: ContentView?
    private var notificationCenter: NotificationCenter
    
    init(center: NotificationCenter = .default) {
        notificationCenter = center
        notificationCenter.addObserver( self, selector: #selector(foreGround), name: UIApplication.willEnterForegroundNotification,object: nil)
        notificationCenter.addObserver( self, selector: #selector(backGround), name: UIApplication.didEnterBackgroundNotification,object: nil)
    }

    deinit {
        notificationCenter.removeObserver(self)
    }
    
    @objc func foreGround(notification: Notification) {
        print(notification, "foreGround")

    }
    
    @objc func backGround(notification: Notification) {
        print(notification, "backGround")
    }
}