UIApplication.willEnterForegroundNotification not fired when Notification Center puts app in background

Ahh, thanks for the clarification. Working now.

my 2 cents for SwiftUI in a cross platform way (Hope help others)

import SwiftUI

#if os(iOS)
import UIKit
#elseif os(macOS)
import AppKit
#endif


struct ContentView: View {
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
        }
        .onAppEnteredBackground {
            print("going back")
        }
    }
}

//MARK: extension


#if os(iOS)
fileprivate let GO_DOWN = UIApplication.didEnterBackgroundNotification
#elseif os(macOS)
fileprivate let GO_DOWN = NSApplication.didResignActiveNotification
#endif



extension View {
    
    func onNotification(
        _ notificationName: Notification.Name,
        perform action: @escaping () -> Void
    ) -> some View {
        onReceive(NotificationCenter.default.publisher(
            for: notificationName
        )) { _ in
            action()
        }
    }
    
    func onAppEnteredBackground(
        perform action: @escaping () -> Void
    ) -> some View {
        onNotification(
            GO_DOWN,
            perform: action
        )
    }
}