Ns Multi Window

Multi-window (9.1): windows, resolvers, and the launch-event migration

Core 9.1 models every UI surface as a NativeWindow with a role ('application' | 'embedded' | 'carplay' | 'externalDisplay') and state ('attached' | 'detached' | 'closed'). Even a single-window app runs through this model.

Reaching windows

import { Application } from '@nativescript/core';

Application.primaryWindow;          // the main app window
Application.activeWindow;           // the one currently focused (differs on iPad side-by-side)
Application.getWindows('all');      // every live window, filterable by role
Application.getWindowById(id);

Per-window environment replaces the deprecated app-level getters: Application.orientation(), Application.systemAppearance() and Application.layoutDirection() are deprecated in favor of Application.primaryWindow?.orientation() etc. — on multi-window iPad the window's values are the truthful ones (a side-by-side window can be compact while the device is landscape).

Providing content: setWindowContentResolver

The launch event is deprecated: it fires only before the first window's content and never for additional windows. The 9.1 shape is a resolver that runs for every window:

Application.setWindowContentResolver((request) => {
  // request: { window, isPrimary, data?, ios?.connectionOptions, android?.intent }
  if (!request.isPrimary) {
    return { moduleName: 'views/aux/aux-root' };   // NavigationEntry, View, or module string
  }
  return 'app-root';
});
Application.run();

Use the ready event for one-time app init. Event ordering per window: Application ready → windowOpen → the raw platform connect/create event → content resolution → contentLoaded → activate and displayed.

Opening a second window

Application.openWindow({ data: { docId: '42' } }); // data crosses as NSUserActivity.userInfo / intent extras

• iOS: requires multi-scene support — gated on UIApplication.sharedApplication.supportsMultipleScenes (iPad; logs Cannot create a new scene - not supported on this device. on iPhone).
• Android: experimental, and the start activity must not use launchMode="singleTask" (the app-template default!) or "singleInstance" in AndroidManifest.xml — Android hands the launch intent to the existing activity instead of opening a second one. Use "singleInstancePerTask" (API 31+) or "standard". The runtime logs exactly this warning; if openWindow "does nothing" on Android, check the manifest first.
• On unsupported platforms the base implementation throws openWindow() is not supported on this platform.

Lifecycle caveat

Listeners registered on a window are dropped immediately after it closes — nothing registered on a window outlives it. Keep cross-window state and subscriptions at the Application level, treat each window's listeners as scoped to its lifetime.

Verified 2026-08 against @nativescript/core 9.1.0-rc.3: types, documented event ordering, deprecations and the exact iOS/Android gating messages read from packages/core/native-window/*, application/application-common.ts, application.ios.ts and application.android.ts. Multi-window flows not exercised on-device from this repo — treat runtime specifics as untested and verify on your target OS versions.