NativeScript · NathanWalker · Jul 21, 2025 · Mar 1, 2025 · Mar 1, 2025 · Mar 1, 2025
diff --git a/packages/core/ui/core/view-base/index.ts b/packages/core/ui/core/view-base/index.ts
@@ -117,12 +117,13 @@ export interface ShowModalOptions {
  * @param criterion - The type of ancestor view we are looking for. Could be a string containing a class name or an actual type.
  * Returns an instance of a view (if found), otherwise undefined.
  */
-export function getAncestor(view: ViewBaseDefinition, criterion: string | { new () }): ViewBaseDefinition {
-	let matcher: (view: ViewBaseDefinition) => boolean = null;
+export function getAncestor<T extends ViewBaseDefinition = ViewBaseDefinition>(view: T, criterion: string | { new () }): T {
+	let matcher: (view: ViewBaseDefinition) => view is T;
+
 	if (typeof criterion === 'string') {
-		matcher = (view: ViewBaseDefinition) => view.typeName === criterion;
+		matcher = (view: ViewBaseDefinition): view is T => view.typeName === criterion;
 	} else {
-		matcher = (view: ViewBaseDefinition) => view instanceof criterion;
+		matcher = (view: ViewBaseDefinition): view is T => view instanceof criterion;
 	}
 
 	for (let parent = view.parent; parent != null; parent = parent.parent) {

diff --git a/packages/core/ui/frame/callbacks/activity-callbacks.ts b/packages/core/ui/frame/callbacks/activity-callbacks.ts
@@ -5,8 +5,6 @@ import { AndroidActivityBackPressedEventData, AndroidActivityNewIntentEventData,
 import { Trace } from '../../../trace';
 import { View } from '../../core/view';
 
-import { _clearEntry, _clearFragment, _getAnimatedEntries, _reverseTransitions, _setAndroidFragmentTransitions, _updateTransitions } from '../fragment.transitions';
-
 import { profile } from '../../../profiling';
 import { isEmbedded, setEmbeddedView } from '../../embedding';
 

diff --git a/packages/core/ui/frame/fragment.transitions.android.ts b/packages/core/ui/frame/fragment.transitions.android.ts
@@ -1,5 +1,5 @@
 // Definitions.
-import { NavigationType } from './frame-common';
+import { NavigationType, TransitionState } from './frame-common';
 import { NavigationTransition, BackstackEntry } from '.';
 
 // Types.
@@ -152,7 +152,7 @@ export function _setAndroidFragmentTransitions(animated: boolean, navigationTran
 			setupCurrentFragmentExplodeTransition(navigationTransition, currentEntry);
 		}
 	} else if (name.indexOf('flip') === 0) {
-		const direction = name.substr('flip'.length) || 'right'; //Extract the direction from the string
+		const direction = name.substring('flip'.length) || 'right'; //Extract the direction from the string
 		const flipTransition = new FlipTransition(direction, navigationTransition.duration, navigationTransition.curve);
 
 		setupNewFragmentCustomTransition(navigationTransition, newEntry, flipTransition);
@@ -282,23 +282,28 @@ export function _getAnimatedEntries(frameId: number): Set<BackstackEntry> {
 
 export function _updateTransitions(entry: ExpandedEntry): void {
 	const fragment = entry.fragment;
+
+	if (!fragment) {
+		return;
+	}
+
 	const enterTransitionListener = entry.enterTransitionListener;
-	if (enterTransitionListener && fragment) {
+	if (enterTransitionListener) {
 		fragment.setEnterTransition(enterTransitionListener.transition);
 	}
 
 	const exitTransitionListener = entry.exitTransitionListener;
-	if (exitTransitionListener && fragment) {
+	if (exitTransitionListener) {
 		fragment.setExitTransition(exitTransitionListener.transition);
 	}
 
 	const reenterTransitionListener = entry.reenterTransitionListener;
-	if (reenterTransitionListener && fragment) {
+	if (reenterTransitionListener) {
 		fragment.setReenterTransition(reenterTransitionListener.transition);
 	}
 
 	const returnTransitionListener = entry.returnTransitionListener;
-	if (returnTransitionListener && fragment) {
+	if (returnTransitionListener) {
 		fragment.setReturnTransition(returnTransitionListener.transition);
 	}
 }
@@ -428,6 +433,16 @@ function addToWaitingQueue(entry: ExpandedEntry): void {
 	entries.add(entry);
 }
 
+function cloneExpandedTransitionListener(expandedTransitionListener: ExpandedTransitionListener) {
+	if (!expandedTransitionListener) {
+		return null;
+	}
+
+	const cloneTransition = expandedTransitionListener.transition.clone();
+
+	return addNativeTransitionListener(expandedTransitionListener.entry, cloneTransition);
+}
+
 function clearExitAndReenterTransitions(entry: ExpandedEntry, removeListener: boolean): void {
 	const fragment: androidx.fragment.app.Fragment = entry.fragment;
 	const exitListener = entry.exitTransitionListener;
@@ -469,15 +484,56 @@ function clearExitAndReenterTransitions(entry: ExpandedEntry, removeListener: bo
 	}
 }
 
+export function _getTransitionState(entry: ExpandedEntry): TransitionState {
+	let transitionState: TransitionState;
+
+	if (entry.enterTransitionListener && entry.exitTransitionListener) {
+		transitionState = {
+			enterTransitionListener: cloneExpandedTransitionListener(entry.enterTransitionListener),
+			exitTransitionListener: cloneExpandedTransitionListener(entry.exitTransitionListener),
+			reenterTransitionListener: cloneExpandedTransitionListener(entry.reenterTransitionListener),
+			returnTransitionListener: cloneExpandedTransitionListener(entry.returnTransitionListener),
+			transitionName: entry.transitionName,
+			entry,
+		};
+	} else {
+		transitionState = null;
+	}
+
+	return transitionState;
+}
+
+export function _restoreTransitionState(snapshot: TransitionState): void {
+	const entry = snapshot.entry as ExpandedEntry;
+
+	if (snapshot.enterTransitionListener) {
+		entry.enterTransitionListener = snapshot.enterTransitionListener;
+	}
+
+	if (snapshot.exitTransitionListener) {
+		entry.exitTransitionListener = snapshot.exitTransitionListener;
+	}
+
+	if (snapshot.reenterTransitionListener) {
+		entry.reenterTransitionListener = snapshot.reenterTransitionListener;
+	}
+
+	if (snapshot.returnTransitionListener) {
+		entry.returnTransitionListener = snapshot.returnTransitionListener;
+	}
+
+	entry.transitionName = snapshot.transitionName;
+}
+
 export function _clearFragment(entry: ExpandedEntry): void {
-	clearEntry(entry, false);
+	clearTransitions(entry, false);
 }
 
 export function _clearEntry(entry: ExpandedEntry): void {
-	clearEntry(entry, true);
+	clearTransitions(entry, true);
 }
 
-function clearEntry(entry: ExpandedEntry, removeListener: boolean): void {
+function clearTransitions(entry: ExpandedEntry, removeListener: boolean): void {
 	clearExitAndReenterTransitions(entry, removeListener);
 
 	const fragment: androidx.fragment.app.Fragment = entry.fragment;
@@ -569,7 +625,7 @@ function setReturnTransition(navigationTransition: NavigationTransition, entry:
 
 function setupNewFragmentSlideTransition(navTransition: NavigationTransition, entry: ExpandedEntry, name: string): void {
 	setupCurrentFragmentSlideTransition(navTransition, entry, name);
-	const direction = name.substr('slide'.length) || 'left'; //Extract the direction from the string
+	const direction = name.substring('slide'.length) || 'left'; //Extract the direction from the string
 	switch (direction) {
 		case 'left':
 			setEnterTransition(navTransition, entry, new androidx.transition.Slide(android.view.Gravity.RIGHT));
@@ -594,7 +650,7 @@ function setupNewFragmentSlideTransition(navTransition: NavigationTransition, en
 }
 
 function setupCurrentFragmentSlideTransition(navTransition: NavigationTransition, entry: ExpandedEntry, name: string): void {
-	const direction = name.substr('slide'.length) || 'left'; //Extract the direction from the string
+	const direction = name.substring('slide'.length) || 'left'; //Extract the direction from the string
 	switch (direction) {
 		case 'left':
 			setExitTransition(navTransition, entry, new androidx.transition.Slide(android.view.Gravity.LEFT));

diff --git a/packages/core/ui/frame/fragment.transitions.d.ts b/packages/core/ui/frame/fragment.transitions.d.ts
@@ -1,4 +1,4 @@
-import { NavigationTransition, BackstackEntry } from '.';
+import { NavigationTransition, BackstackEntry, TransitionState } from '.';
 
 /**
  * @private
@@ -20,6 +20,14 @@ export function _updateTransitions(entry: BackstackEntry): void;
  * Reverse transitions from entry to fragment if any.
  */
 export function _reverseTransitions(previousEntry: BackstackEntry, currentEntry: BackstackEntry): boolean;
+/**
+ * @private
+ */
+export function _getTransitionState(entry: BackstackEntry): TransitionState;
+/**
+ * @private
+ */
+export function _restoreTransitionState(snapshot: TransitionState): void;
 /**
  * @private
  * Called when entry is removed from backstack (either back navigation or

diff --git a/packages/core/ui/frame/frame-common.ts b/packages/core/ui/frame/frame-common.ts
@@ -76,13 +76,13 @@ export class FrameBase extends CustomLayoutView {
 			return true;
 		} else if (top) {
 			let parentFrameCanGoBack = false;
-			let parentFrame = <FrameBase>getAncestor(top, 'Frame');
+			let parentFrame = getAncestor(top, 'Frame');
 
 			while (parentFrame && !parentFrameCanGoBack) {
 				if (parentFrame && parentFrame.canGoBack()) {
 					parentFrameCanGoBack = true;
 				} else {
-					parentFrame = <FrameBase>getAncestor(parentFrame, 'Frame');
+					parentFrame = getAncestor(parentFrame, 'Frame');
 				}
-			let parentFrame = getAncestor(top, 'Frame');
-
-			while (parentFrame && !parentFrameCanGoBack) {
-				if (parentFrame && parentFrame.canGoBack()) {
-					parentFrameCanGoBack = true;
-				} else {
-					parentFrame = <FrameBase>getAncestor(parentFrame, 'Frame');
-					parentFrame = getAncestor(parentFrame, 'Frame');
-				}
+			// Before: let parentFrame = getAncestor(top, 'Frame');
+			let parentFrame: FrameBase | undefined = getAncestor(top, FrameBase);
+
+			while (parentFrame && !parentFrameCanGoBack) {
+				if (parentFrame && parentFrame.canGoBack()) {
+					parentFrameCanGoBack = true;
+				} else {
+					// Before: parentFrame = getAncestor(parentFrame, 'Frame');
+					parentFrame = getAncestor(parentFrame, FrameBase);
+				}
+			}
-			let parentFrame = getAncestor(top, 'Frame');
-
-			while (parentFrame && !parentFrameCanGoBack) {
-				if (parentFrame && parentFrame.canGoBack()) {
-					parentFrameCanGoBack = true;
-				} else {
-					parentFrame = <FrameBase>getAncestor(parentFrame, 'Frame');
-					parentFrame = getAncestor(parentFrame, 'Frame');
-				}
+			// Before: let parentFrame = getAncestor(top, 'Frame');
+			let parentFrame: FrameBase | undefined = getAncestor(top, FrameBase);
+
+			while (parentFrame && !parentFrameCanGoBack) {
+				if (parentFrame && parentFrame.canGoBack()) {
+					parentFrameCanGoBack = true;
+				} else {
+					// Before: parentFrame = getAncestor(parentFrame, 'Frame');
+					parentFrame = getAncestor(parentFrame, FrameBase);
+				}
+			}
 			}
 
@@ -122,7 +122,6 @@ export class FrameBase extends CustomLayoutView {
 	@profile
 	public onLoaded() {
 		super.onLoaded();
-
 		this._processNextNavigationEntry();
 	}
 
@@ -323,9 +322,10 @@ export class FrameBase extends CustomLayoutView {
 	}
 
 	private isNestedWithin(parentFrameCandidate: FrameBase): boolean {
-		let frameAncestor: FrameBase = this;
+		let frameAncestor = this as FrameBase;
+
 		while (frameAncestor) {
-			frameAncestor = <FrameBase>getAncestor(frameAncestor, FrameBase);
+			frameAncestor = getAncestor(frameAncestor, FrameBase);
 			if (frameAncestor === parentFrameCandidate) {
 				return true;
 			}