From 4e62b00ddb84823654c864d32e298db286068733 Mon Sep 17 00:00:00 2001
From: Dimitris-Rafail Katsampas <katsampasdr@gmail.com>
Date: Thu, 2 Mar 2023 18:39:32 +0200
Subject: [PATCH] fix(core): Frame to Page property propagation (#10225)

---
 packages/core/ui/frame/frame-common.ts  | 15 ++++++++++++---
 packages/core/ui/frame/index.android.ts | 10 ++++++----
 packages/core/ui/page/index.ios.ts      |  4 +++-
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/packages/core/ui/frame/frame-common.ts b/packages/core/ui/frame/frame-common.ts
index 94ffc0b1a..f16484b23 100644
--- a/packages/core/ui/frame/frame-common.ts
+++ b/packages/core/ui/frame/frame-common.ts
@@ -43,6 +43,14 @@ export class FrameBase extends CustomLayoutView {
 
 	public actionBarVisibility: 'auto' | 'never' | 'always';
 	public _currentEntry: BackstackEntry;
+
+	/**
+	 * A reference of current page that is set earlier than current entry.
+	 * Using this property, methods like 'eachChildView' and '_childrenCount' gain access to page view
+	 * just in time for calls like '_addView' to perform view-tree iterations.
+	 */
+	public _resolvedPage: Page;
+
 	public _animationInProgress = false;
 	public _executingContext: NavigationContext;
 	public _isInFrameStack = false;
@@ -238,6 +246,8 @@ export class FrameBase extends CustomLayoutView {
 		// In case we navigated forward to a page that was in the backstack
 		// with clearHistory: true
 		if (!newPage.frame) {
+			this._resolvedPage = newPage;
+
 			this._addView(newPage);
 			newPage._frame = this;
 		}
@@ -456,7 +466,6 @@ export class FrameBase extends CustomLayoutView {
 		if (this._currentEntry) {
 			return this._currentEntry.resolvedPage;
 		}
-
 		return null;
 	}
 
@@ -508,7 +517,7 @@ export class FrameBase extends CustomLayoutView {
 	}
 
 	get _childrenCount(): number {
-		if (this.currentPage) {
+		if (this._resolvedPage) {
 			return 1;
 		}
 
@@ -516,7 +525,7 @@ export class FrameBase extends CustomLayoutView {
 	}
 
 	public eachChildView(callback: (child: View) => boolean) {
-		const page = this.currentPage;
+		const page = this._resolvedPage;
 		if (page) {
 			callback(page);
 		}
diff --git a/packages/core/ui/frame/index.android.ts b/packages/core/ui/frame/index.android.ts
index 1b926728e..337198e68 100644
--- a/packages/core/ui/frame/index.android.ts
+++ b/packages/core/ui/frame/index.android.ts
@@ -913,6 +913,8 @@ class FragmentCallbacksImplementation implements AndroidFragmentCallbacks {
 			return null;
 		}
 
+		frame._resolvedPage = page;
+
 		if (page.parent === frame) {
 			// If we are navigating to a page that was destroyed
 			// reinitialize its UI.
@@ -920,6 +922,10 @@ class FragmentCallbacksImplementation implements AndroidFragmentCallbacks {
 				const context = (container && container.getContext()) || (inflater && inflater.getContext());
 				page._setupUI(context);
 			}
+
+			if (frame.isLoaded && !page.isLoaded) {
+				page.callLoaded();
+			}
 		} else {
 			if (!frame._styleScope) {
 				// Make sure page will have styleScope even if parents don't.
@@ -929,10 +935,6 @@ class FragmentCallbacksImplementation implements AndroidFragmentCallbacks {
 			frame._addView(page);
 		}
 
-		if (frame.isLoaded && !page.isLoaded) {
-			page.callLoaded();
-		}
-
 		const savedState = entry.viewSavedState;
 		if (savedState) {
 			(<android.view.View>page.nativeViewProtected).restoreHierarchyState(savedState);
diff --git a/packages/core/ui/page/index.ios.ts b/packages/core/ui/page/index.ios.ts
index d6bc16367..bd2bbab0e 100644
--- a/packages/core/ui/page/index.ios.ts
+++ b/packages/core/ui/page/index.ios.ts
@@ -120,7 +120,7 @@ class UIViewControllerImpl extends UIViewController {
 			return;
 		}
 
-		const frame = this.navigationController ? (<any>this.navigationController).owner : null;
+		const frame: Frame = this.navigationController ? (<any>this.navigationController).owner : null;
 		const newEntry = this[ENTRY];
 
 		// Don't raise event if currentPage was showing modal page.
@@ -130,6 +130,8 @@ class UIViewControllerImpl extends UIViewController {
 		}
 
 		if (frame) {
+			frame._resolvedPage = owner;
+
 			if (!owner.parent) {
 				owner._frame = frame;
 				if (!frame._styleScope) {