macos-patterns

macOS Platform Patterns

Window Management

Three scene types for Mac apps:

@main
struct MyApp: App {
    var body: some Scene {
        // Main window — users can open multiple instances
        WindowGroup {
            ContentView()
        }
        .defaultSize(width: 900, height: 600)

        // Single utility window
        Window("Inspector", id: "inspector") {
            InspectorView()
        }
        .defaultSize(width: 300, height: 400)

        // Document-based app
        DocumentGroup(newDocument: MyDocument()) { file in
            DocumentEditor(document: file.$document)
        }
    }
}

Menu Bar Customization (CommandMenu + FocusedValue)

CommandMenu closures run at the App scene level — outside the view hierarchy. They CANNOT access view @State directly. Use @FocusedValue to bridge view state to menu actions.

// 1. Define a FocusedValue key using @Entry
extension FocusedValues {
    @Entry var activeDocument: DocumentViewModel?
}

// 2. ViewModel — @Observable only (NOT ObservableObject)
@Observable @MainActor
class DocumentViewModel {
    var content = ""
    func save() { /* persist */ }
    func togglePreview() { /* toggle */ }
}

// 3. Publish from active view using .focusedValue()
struct DocumentView: View {
    @State var viewModel = DocumentViewModel()
    var body: some View {
        EditorContent(viewModel: viewModel)
            .focusedValue(\.activeDocument, viewModel)  // REQUIRED — publish to menu bar
    }
}

// 4. Consume in App via @FocusedValue and wire ALL menu actions
@main
struct MyApp: App {
    @FocusedValue(\.activeDocument) private var document

    var body: some Scene {
        WindowGroup { DocumentView() }

        CommandMenu("Document") {
            Button("Save") { document?.save() }
                .keyboardShortcut("s", modifiers: .command)
                .disabled(document == nil)
            Button("Toggle Preview") { document?.togglePreview() }
                .keyboardShortcut("p", modifiers: [.command, .option])
                .disabled(document == nil)
        }

        CommandGroup(replacing: .newItem) {
            Button("New Document") { document?.createNew() }
                .keyboardShortcut("n", modifiers: .command)
                .disabled(document == nil)
        }
    }
}