From bf17c3be3a3e0f44de51f8f3da7e4f14b036ffe5 Mon Sep 17 00:00:00 2001
From: chrsmys <chris@nschris.com>
Date: Wed, 19 Feb 2025 14:51:19 -0800
Subject: [PATCH] Fix force RTL support on new architecture. (#49455)

Summary:
This fixes an issue in Fabric where changing the layout direction and then reloading the JS bundle did not honor the layout direction until the app was restarted on iOS. This now calls  `_updateLayoutContext` whenever RCTSurfaceView is recreated which happens on bundle reload. This is not an issue on the old architecture because the layout direction is determined within the [SurfaceViews](https://github.com/facebook/react-native/blob/acdddef48eb60b002c954d7d2447cb9c2883c8b3/packages/react-native/React/Views/RCTRootShadowView.m#L18) which were recreated on bundle reload.

## Related Issues:
- https://github.com/react-native-community/discussions-and-proposals/issues/847
- https://github.com/facebook/react-native/issues/49451
- https://github.com/facebook/react-native/issues/48311
- https://github.com/facebook/react-native/issues/45661

## How can we take this further?
If we want to make it so that it doesn't require an entire bundle reload for RTL to take effect I believe these are the steps that would need to be taken:
- Make it so [RCTI18nManager](https://github.com/facebook/react-native/blob/acdddef48eb60b002c954d7d2447cb9c2883c8b3/packages/react-native/React/CoreModules/RCTI18nManager.mm#L52) exports isRTL as a method instead of consts
- Send Notification Center notif when RTL is forced on or off
- Listen for that notification RCTSurfaceView and call _updateLayoutContext similar to UIContentSizeCategoryDidChangeNotification.

## Changelog:

[iOS] [FIXED] - Layout direction changes are now honored on bundle reload.

<!-- Help reviewers and the release process by writing your own changelog entry.

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Pull Request resolved: https://github.com/facebook/react-native/pull/49455

Test Plan:
On the new architecture change force the layout direction and reload the bundle:
```
import React, { useCallback } from "react";
import { Button, I18nManager, StyleSheet, Text, View } from "react-native";
import RNRestart from "react-native-restart";

export default function Explore() {
    const onApplyRTL = useCallback(() => {
        if (!I18nManager.isRTL) {
            I18nManager.forceRTL(true);
            RNRestart.restart();
        }
    }, []);

    const onApplyLTR = useCallback(() => {
        if (I18nManager.isRTL) {
            I18nManager.forceRTL(false);
            RNRestart.restart();
        }
    }, []);

    return (
        <View style={styles.area}>
            <Text>Test Block</Text>
            <View style={styles.testBlock}>
                <Text>Leading</Text>
                <Text>Trailing</Text>
            </View>
            <Button title={"Apply RTL"} onPress={onApplyRTL} />
            <Button title={"Apply LTR"} onPress={onApplyLTR} />
        </View>
    );
}

const styles = StyleSheet.create({
    area: {
        marginVertical: 50,
        paddingHorizontal: 24,
    },
    testBlock: {
        paddingVertical: 10,
        flexDirection: "row",
        justifyContent: "space-between",
    },
});

```

https://github.com/user-attachments/assets/0eab0d79-de3f-4eeb-abd0-439ba4fe25c0

Reviewed By: cortinico, cipolleschi

Differential Revision: D69797645

Pulled By: NickGerleman

fbshipit-source-id: 97499621f3dd735d466f5119e0f2a0eccf1c3c05
---
 packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm b/packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm
index 7b3ce5918ce..3906df778bc 100644
--- a/packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm
+++ b/packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm
@@ -143,6 +143,7 @@ using namespace facebook::react;
 
   if (!_view) {
     _view = [[RCTSurfaceView alloc] initWithSurface:(RCTSurface *)self];
+    [self _updateLayoutContext];
     _touchHandler = [RCTSurfaceTouchHandler new];
     [_touchHandler attachToView:_view];
   }