From 17bdd2ad967c024d0f15584560e36683e321b19b Mon Sep 17 00:00:00 2001
From: Igor Randjelovic <rigor789@gmail.com>
Date: Tue, 16 Mar 2021 02:54:31 +0100
Subject: [PATCH] fix(bottom-navigation): fragment handling (#9243)

---
 .../bottom-navigation.android.ts              |  8 ++++---
 nativescript-core/ui/tabs/tabs.android.ts     | 23 ++++++++++++++-----
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/nativescript-core/ui/bottom-navigation/bottom-navigation.android.ts b/nativescript-core/ui/bottom-navigation/bottom-navigation.android.ts
index 6aed0101c..6f133e4f9 100644
--- a/nativescript-core/ui/bottom-navigation/bottom-navigation.android.ts
+++ b/nativescript-core/ui/bottom-navigation/bottom-navigation.android.ts
@@ -540,7 +540,9 @@ export class BottomNavigation extends TabNavigationBase {
 
             if (fragment != null) {
                 fragment.setMenuVisibility(true);
-                fragment.setUserVisibleHint(true);
+                // commenting out as it fixes rare crash when going
+                // back from deeply nested/modally shown fragments
+                // fragment.setUserVisibleHint(true);
             }
 
             this._currentFragment = fragment;
@@ -582,8 +584,8 @@ export class BottomNavigation extends TabNavigationBase {
                     fragmentExitTransition.setResetOnTransitionEnd(true);
                 }
                 if (fragment && fragment.isAdded() && !fragment.isRemoving()) {
-                    const pfm = (<any>fragment).getParentFragmentManager ? (<any>fragment).getParentFragmentManager() : null;
-                    if (pfm && !pfm.isDestroyed()) {
+                    const pfm = (<any>fragment).getParentFragmentManager ? (<any>fragment).getParentFragmentManager() : fragmentManager;
+                    if (pfm) {
                         try {
                             if (pfm.isStateSaved()) {
                                 pfm.beginTransaction().remove(fragment).commitNowAllowingStateLoss();
diff --git a/nativescript-core/ui/tabs/tabs.android.ts b/nativescript-core/ui/tabs/tabs.android.ts
index 7b85c489a..b440a7aca 100644
--- a/nativescript-core/ui/tabs/tabs.android.ts
+++ b/nativescript-core/ui/tabs/tabs.android.ts
@@ -205,13 +205,24 @@ function initializeNativeClasses() {
         }
 
         destroyItem(container: android.view.ViewGroup, position: number, object: java.lang.Object): void {
-            if (!this.mCurTransaction) {
-                const fragmentManager = this.owner._getFragmentManager();
-                this.mCurTransaction = fragmentManager.beginTransaction();
-            }
-
             const fragment: androidx.fragment.app.Fragment = <androidx.fragment.app.Fragment>object;
-            this.mCurTransaction.detach(fragment);
+
+            if(fragment.isAdded()) {
+              if (!this.mCurTransaction) {
+                try {
+                  // try to get the correct FragmentManager
+                  // @ts-ignore
+                  const fragmentManager = fragment.getParentFragmentManager()
+                  this.mCurTransaction = fragmentManager.beginTransaction();
+                } catch (err) {
+                  const fragmentManager = this.owner._getFragmentManager();
+                  this.mCurTransaction = fragmentManager.beginTransaction();
+                }
+
+              }
+
+              this.mCurTransaction.detach(fragment);
+            }
 
             if (this.mCurrentPrimaryItem === fragment) {
                 this.mCurrentPrimaryItem = null;