Aim:

• I have a swiftUI app that uses Window scene
• When the user closes the red window, I would like call f1()

My attempt:

onDisappear doesn’t seem to be called when user closes the macOS app window

Question:

1. In macOS (SwiftUI) how do I detect a window is closed by the user?
2. Am I missing something?

Code

App

@main
struct DemoApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        
        Window("test", id: "test") {
            Color.red
                .onDisappear {
                    print("onDisappear")
                    f1()
                }
        }
    }
    
    func f1() {
        print("f1 called")
    }
}

ContentView

struct ContentView: View {
    @Environment(\.openWindow) private var openWindow
    var body: some View {
        Button("show red") {
            openWindow(id: "test")
        }
    }
}

>Solution :

You can use the NSWindow.willCloseNotification notification:

struct ContentView: View {
    
    var body: some View {
        
        Text("xyz")
            .onReceive(NotificationCenter.default.publisher(for: NSWindow.willCloseNotification)) { newValue in
                print("close")
            }
    }
}