fix(ios): hide leaving view after nav transition to avoid flicker (#19691)

fixes #19674

Author: liamdebeasi

core/src/utils/transition/index.ts

@@ -243,6 +243,19 @@ const setZIndex = (
   }
 };
 
+export const getIonPageElement = (element: HTMLElement) => {
+  if (element.classList.contains('ion-page')) {
+    return element;
+  }
+
+  const ionPage = element.querySelector(':scope > .ion-page, :scope > ion-nav, :scope > ion-tabs');
+  if (ionPage) {
+    return ionPage;
+  }
+  // idk, return the original element so at least something animates and we don't have a null pointer
+  return element;
+};
+
 export interface TransitionOptions extends NavOptions {
   progressCallback?: ((ani: IonicAnimation | Animation | undefined) => void);
   baseEl: any;

core/src/utils/transition/ios.transition.ts

@@ -1,6 +1,6 @@
 import { IonicAnimation } from '../../interface';
 import { createAnimation } from '../animation/animation';
-import { TransitionOptions } from '../transition';
+import { TransitionOptions, getIonPageElement } from '../transition';
 
 const DURATION = 540;
 const addSafeArea = (val: number, side = 'top'): string => {
@@ -376,6 +376,13 @@ export const iosTransitionAnimation = (navEl: HTMLElement, opts: TransitionOptio
           .beforeClearStyles([OPACITY])
           .fromTo('transform', `translateX(${CENTER})`, (isRTL ? 'translateX(-100%)' : 'translateX(100%)'));
 
+        const leavingPage = getIonPageElement(leavingEl) as HTMLElement;
+        rootAnimation.afterAddWrite(() => {
+          if (rootAnimation.getDirection() === 'normal') {
+            leavingPage.style.setProperty('display', 'none');
+          }
+        });
+
       } else {
         // leaving content, forward direction
         leavingContent

core/src/utils/transition/md.transition.ts

@@ -1,6 +1,6 @@
 import { IonicAnimation } from '../../interface';
 import { createAnimation } from '../animation/animation';
-import { TransitionOptions } from '../transition';
+import { TransitionOptions, getIonPageElement } from '../transition';
 
 export const mdTransitionAnimation = (_: HTMLElement, opts: TransitionOptions): IonicAnimation => {
   const OFF_BOTTOM = '40px';
@@ -59,16 +59,3 @@ export const mdTransitionAnimation = (_: HTMLElement, opts: TransitionOptions):
 
   return rootTransition;
 };
-
-const getIonPageElement = (element: HTMLElement) => {
-  if (element.classList.contains('ion-page')) {
-    return element;
-  }
-
-  const ionPage = element.querySelector(':scope > .ion-page, :scope > ion-nav, :scope > ion-tabs');
-  if (ionPage) {
-    return ionPage;
-  }
-  // idk, return the original element so at least something animates and we don't have a null pointer
-  return element;
-};