From bd7c686aaf55d26b2b483905bd5e0a453429cabd Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@users.noreply.github.com>
Date: Thu, 19 Nov 2020 22:02:32 -0300
Subject: [PATCH] feat(core): allow app to start without a root view (#9056)

---
 packages/core/application/application-interfaces.ts | 2 +-
 packages/core/application/index.android.ts          | 2 +-
 packages/core/application/index.d.ts                | 3 ++-
 packages/core/application/index.ios.ts              | 4 +++-
 packages/core/ui/frame/index.android.ts             | 6 ++++++
 5 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/packages/core/application/application-interfaces.ts b/packages/core/application/application-interfaces.ts
index 9427f68a4..13ea7fa5c 100644
--- a/packages/core/application/application-interfaces.ts
+++ b/packages/core/application/application-interfaces.ts
@@ -20,7 +20,7 @@ export interface ApplicationEventData extends EventData {
 }
 
 export interface LaunchEventData extends ApplicationEventData {
-	root?: View;
+	root?: View | null;
 	savedInstanceState?: any /* android.os.Bundle */;
 }
 
diff --git a/packages/core/application/index.android.ts b/packages/core/application/index.android.ts
index c3dbacd38..50ce16597 100644
--- a/packages/core/application/index.android.ts
+++ b/packages/core/application/index.android.ts
@@ -191,7 +191,7 @@ export function addCss(cssText: string, attributeScoped?: boolean): void {
 const CALLBACKS = '_callbacks';
 
 export function _resetRootView(entry?: NavigationEntry | string): void {
-	const activity = androidApp.foregroundActivity;
+	const activity = androidApp.foregroundActivity || androidApp.startActivity;
 	if (!activity) {
 		throw new Error('Cannot find android activity.');
 	}
diff --git a/packages/core/application/index.d.ts b/packages/core/application/index.d.ts
index d2cb041a4..07416d5f8 100644
--- a/packages/core/application/index.d.ts
+++ b/packages/core/application/index.d.ts
@@ -103,8 +103,9 @@ export interface LaunchEventData extends ApplicationEventData {
 	/**
 	 * The root view for this Window on iOS or Activity for Android.
 	 * If not set a new Frame will be created as a root view in order to maintain backwards compatibility.
+	 * If explicitly set to null, there will be no root view.
 	 */
-	root?: View;
+	root?: View | null;
 
 	savedInstanceState?: any /* android.os.Bundle */;
 }
diff --git a/packages/core/application/index.ios.ts b/packages/core/application/index.ios.ts
index e502b4758..f36cafb70 100644
--- a/packages/core/application/index.ios.ts
+++ b/packages/core/application/index.ios.ts
@@ -207,7 +207,9 @@ export class iOSApplication implements iOSApplicationDefinition {
 
 		// this._window will be undefined when NS app is embedded in a native one
 		if (this._window) {
-			this.setWindowContent(args.root);
+			if (args.root !== null) {
+				this.setWindowContent(args.root);
+			}
 		} else {
 			this._window = UIApplication.sharedApplication.delegate.window;
 		}
diff --git a/packages/core/ui/frame/index.android.ts b/packages/core/ui/frame/index.android.ts
index 9203131ee..ccfc3a918 100644
--- a/packages/core/ui/frame/index.android.ts
+++ b/packages/core/ui/frame/index.android.ts
@@ -1301,13 +1301,19 @@ class ActivityCallbacksImplementation implements AndroidActivityCallbacks {
 		if (!rootView) {
 			const mainEntry = application.getMainEntry();
 			const intent = activity.getIntent();
+			// useful for integrations that would like to set rootView asynchronously after app launch
+			let shouldRootViewBeEmpty = false;
 
 			if (fireLaunchEvent) {
 				// entry point for Angular and Vue frameworks
 				rootView = notifyLaunch(intent, <any>savedInstanceState, null);
+				shouldRootViewBeEmpty = rootView === null;
 			}
 
 			if (!rootView) {
+				if (shouldRootViewBeEmpty) {
+					return;
+				}
 				// entry point for NS Core
 				if (!mainEntry) {
 					// Also handles scenarios with Angular and Vue where the notifyLaunch didn't return a root view.