fix(iOS): modal content flicker during enter transition on iPad

apps/src/tests/Test3345.tsx

@@ -0,0 +1,49 @@
+import React from 'react';
+import { View, Button } from 'react-native';
+import { NavigationContainer } from '@react-navigation/native';
+import { createNativeStackNavigator } from '@react-navigation/native-stack';
+
+const Stack = createNativeStackNavigator();
+
+function HomeScreen({ navigation }) {
+  return (
+    // In original repro SafeAreaView from `react-native` has been used here. 
+    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
+      <Button
+        title="Open Modal"
+        onPress={() => navigation.navigate('Modal')}
+      />
+    </View>
+  );
+}
+
+function ModalScreen() {
+  const onLayout = (event) => {
+    const { width } = event.nativeEvent.layout;
+    console.log('Modal width:', width);
+  };
+  return (
+    <View style={{ flex: 1, width: '100%', alignSelf: 'center', paddingHorizontal: 16, backgroundColor: 'green' }} onLayout={onLayout}>
+      <View style={{ flex: 1, backgroundColor: 'purple' }} />
+    </View>
+  );
+}
+
+function App() {
+  return (
+    <NavigationContainer>
+      <Stack.Navigator>
+        <Stack.Screen name="Home" component={HomeScreen} />
+        <Stack.Screen
+          name="Modal"
+          component={ModalScreen}
+          options={{
+            presentation: 'modal'
+          }}
+        />
+      </Stack.Navigator>
+    </NavigationContainer>
+  );
+}
+
+export default App;

apps/src/tests/index.ts

@@ -168,3 +168,4 @@ export { default as TestBottomTabs } from './TestBottomTabs';
 export { default as TestScreenStack } from './TestScreenStack';
 export { default as TestSplitView } from './TestSplitView';
 export { default as TestSafeAreaViewIOS } from './TestSafeAreaViewIOS';
+export { default as Test3345 } from './Test3345';

ios/RNSScreen.mm

@@ -1464,6 +1464,14 @@ - (void)updateLayoutMetrics:(const react::LayoutMetrics &)layoutMetrics
   _newLayoutMetrics = layoutMetrics;
   _oldLayoutMetrics = oldLayoutMetrics;
   UIViewController *parentVC = self.reactViewController.parentViewController;
+
+  if (parentVC == nil && [self isKindOfClass:RNSModalScreen.class]) {
+    // If we're in modal presentation, we don't want to set the frame from RN,
+    // as the available space is most likely restriced & differs from what Yoga
+    // resolves during firt layout. We want to rely on native layout here.
+    return;
+  }
+
   if (parentVC == nil || ![parentVC isKindOfClass:[RNSNavigationController class]]) {
     [super updateLayoutMetrics:layoutMetrics oldLayoutMetrics:oldLayoutMetrics];
   }