Module scene 

Scenes and commands — what an app is, above its views.

crate::app::run builds one WindowGroup and stops there. A real macOS app is several scenes: the window group, the preferences window Settings puts behind ⌘, — a menu-bar item, a second window — and a menu bar described by Commands. This module builds each of them, and the tuples that hold several at once, so crate::app::run_scene can be given a whole app rather than one window.

use swiftui_native::{app, scene, views};

app::run_scene(|| {
    scene::commands(
        scene::group(vec![
            scene::window_group(|| views::text("main")),
            scene::settings(|| views::text("preferences")),
            scene::menu_bar_extra("Status", "star", || views::text("menu")),
        ]),
        vec![scene::command_menu("Extras", || views::button("Do it", || {}))],
    )
});

Why the content closures are borrowed

Every initialiser here takes its content as @noescape — xyXE in the mangling, not yc — so it calls the closure before returning and keeps the value, not the closure. A borrowed crate::abi::ClosureCtx on the stack is therefore correct, and leaking one (as a sheet’s content must be) would leak once per read of App.body, which SwiftUI does repeatedly.

What is synthesised and what is SwiftUI’s

Nothing here is a Swift wrapper: each scene is SwiftUI’s own type, instantiated by calling its own initialiser with the arguments in the registers its ABI names. _TupleScene and TupleCommandContent are what SceneBuilder and CommandsBuilder build — those builders are @_alwaysEmitIntoClient and export no symbol, so the binding calls what their bodies call.

Structs

CommandsHandle

A value conforming to SwiftUI’s Commands — one menu, or a tuple of them.

SceneHandle

A value conforming to SwiftUI’s Scene — a window, a settings pane, a menu-bar item, or a tuple of them.

Enums

CommandPlacement

Where in the standard menu bar a command_group goes.

Relative

Where a group sits relative to the placement it names.

Functions

command_group

CommandGroup(replacing:/after:/before: placement) { content } — items added to, or in place of, one of the standard menu groups.

command_menu

CommandMenu(title) { content } — a whole new menu in the menu bar.

commands

.commands { … } on a scene — the app’s menu bar.

group

Several scenes as one — _TupleScene<(A, B, …)>.

menu_bar_extra

MenuBarExtra(title, systemImage: image) { content } — an item in the system menu bar, with a menu of its own.

settings

Settings { content } — the window behind ⌘, on macOS.

window

Window(title, id: id) { content } — a single window, not a group.

window_group

WindowGroup { content } — the app’s main window, and as many more as the user opens.