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")
        }
    }
}

For a "SwiftUI way" to do this, check out the environment property controlActiveState. This value will be set to .inactive when the window loses focus, and when the window is closed.

struct ContentView: View {
    @Environment(\.controlActiveState) private var controlActiveState

    var body: some View {
        Text("Hello, World!")
            .onChange(of: controlActiveState) { newValue in
                switch newValue {
                case .key, .active:
                    break
                case .inactive:
                    // Do your stuff.
                @unknown default:
                    break
                }
            }
    }
}