From fd9f2e04bdf44c1c70008eaf46b02205106e3b42 Mon Sep 17 00:00:00 2001
From: Kacper Kafara <kacper.kafara@swmansion.com>
Date: Tue, 2 Jan 2024 14:19:03 +0100
Subject: [PATCH] fix(iOS): app freeze when navigating back from any modal
 nested in contained modal (#1996)

## Description

Updated logic in `RNSScreenStackView#setModalViewControllers:` so that
it handles case when navigating back from top-level VC that was not
presented
by the screen stack itself, as it happens with
`UIModalPresentationCurrentContext` &
`UIModalPresentationOverCurrentContext`.

Fixes #1813

## Changes

We now check whether the top-level VC should be dismissed by the stack
being asked.

## Test code and steps to reproduce

See #1813 for reproduction steps.

I'm also adding these in `Example` application.

## Checklist

- [x] Included code example that can be used to test this change
- [x] Ensured that CI passes
---
 Example/src/screens/Modals.tsx | 14 ++++++++++++++
 TestsExample/App.js            |  2 +-
 ios/RNSScreenStack.mm          | 16 ++++++++++++++--
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/Example/src/screens/Modals.tsx b/Example/src/screens/Modals.tsx
index 47badffbc5..a98f7c3bae 100644
--- a/Example/src/screens/Modals.tsx
+++ b/Example/src/screens/Modals.tsx
@@ -11,6 +11,7 @@ type StackParamList = {
   Modal: undefined;
   FullscreenModal: undefined;
   Alert: undefined;
+  ContainedModal: undefined;
 };
 
 interface MainScreenProps {
@@ -25,6 +26,10 @@ const MainScreen = ({ navigation }: MainScreenProps): JSX.Element => (
       onPress={() => navigation.navigate('FullscreenModal')}
     />
     <Button title="Open alert" onPress={() => navigation.navigate('Alert')} />
+    <Button
+      title="Open contained modal"
+      onPress={() => navigation.navigate('ContainedModal')}
+    />
     <Button onPress={() => navigation.pop()} title="🔙 Back to Examples" />
   </View>
 );
@@ -41,6 +46,10 @@ const ModalScreen = ({ navigation }: ModalScreenProps): JSX.Element => (
       onPress={() => navigation.push('FullscreenModal')}
     />
     <Button title="Open alert" onPress={() => navigation.navigate('Alert')} />
+    <Button
+      title="Open contained modal"
+      onPress={() => navigation.navigate('ContainedModal')}
+    />
     <Button title="Go back" onPress={() => navigation.goBack()} />
   </View>
 );
@@ -68,6 +77,11 @@ const App = (): JSX.Element => (
       component={ModalScreen}
       options={{ stackPresentation: 'fullScreenModal' }}
     />
+    <Stack.Screen
+      name="ContainedModal"
+      component={ModalScreen}
+      options={{ stackPresentation: 'containedModal' }}
+    />
     <Stack.Screen
       name="Alert"
       component={Alert}
diff --git a/TestsExample/App.js b/TestsExample/App.js
index 8e348b1297..90d1085d49 100644
--- a/TestsExample/App.js
+++ b/TestsExample/App.js
@@ -90,9 +90,9 @@ import Test1683 from './src/Test1683';
 import Test1726 from './src/Test1726';
 import Test1791 from './src/Test1791';
 import Test1802 from './src/Test1802';
+import Test1829 from './src/Test1829';
 import Test1844 from './src/Test1844';
 import Test1864 from './src/Test1864';
-import Test1829 from './src/Test1829';
 import Test1981 from './src/Test1981';
 
 enableFreeze(true);
diff --git a/ios/RNSScreenStack.mm b/ios/RNSScreenStack.mm
index be79f080d0..71dbaee5fc 100644
--- a/ios/RNSScreenStack.mm
+++ b/ios/RNSScreenStack.mm
@@ -501,15 +501,27 @@ - (void)setModalViewControllers:(NSArray<UIViewController *> *)controllers
     }
   }
 
-  // changeRootController does not have presentedViewController but it does not mean that no modals are in presentation,
-  // so we need to find top-level controller manually
+  // changeRootController does not have presentedViewController but it does not mean that no modals are in presentation;
+  // modals could be presented by another stack (nested / outer), third-party view controller or they could be using
+  // UIModalPresentationCurrentContext / UIModalPresentationOverCurrentContext presentation styles; in the last case
+  // for some reason system asks top-level (react root) vc to present instead of our stack, despite the fact that
+  // `definesPresentationContext` returns `YES` for UINavigationController.
+  // So we first need to find top-level controller manually:
   UIViewController *reactRootVc = [self findReactRootViewController];
   UIViewController *topMostVc = [RNSScreenStackView findTopMostPresentedViewControllerFromViewController:reactRootVc];
 
   if (topMostVc != reactRootVc) {
     changeRootController = topMostVc;
+
+    // Here we handle just the simplest case where the top level VC was dismissed. In any more complex
+    // scenario we will still have problems, see: https://github.com/software-mansion/react-native-screens/issues/1813
+    if ([_presentedModals containsObject:topMostVc] && ![controllers containsObject:topMostVc]) {
+      [changeRootController dismissViewControllerAnimated:YES completion:finish];
+      return;
+    }
   }
 
+  // We didn't detect any controllers for dismissal, thus we start presenting new VCs
   finish();
 }