Fix GestureDetector unresponsive after display:none toggle (New Arch) (#3964)

## Description

On New Architecture, when a parent view has display: 'none' and siblings
change while hidden, the native UIView backing a component may be
recycled and replaced. The React view tag stays the same but the UIView
instance changes, causing gesture recognizers to be lost.

This adds a reattachHandlersIfNeeded check in flushOperations that
re-binds handlers whose native view has changed. The check is a fast
no-op (pointer comparison) when views haven't been recycled.

Fixes #3937

## Test plan

Tested with both v2 (Gesture.Tap()) and v3 (useTapGesture) APIs on iOS
simulator (New Architecture).

Minimal repro to verify the fix:

```ts
import React, { useCallback, useState } from 'react';
import { Button, StyleSheet, Text, View } from 'react-native';
import {
  Gesture,
  GestureDetector,
  useTapGesture,
} from 'react-native-gesture-handler';

export default function DisplayNone() {
  const [tapCountV2, setTapCountV2] = useState(0);
  const [tapCountV3, setTapCountV3] = useState(0);

  const tapV2 = Gesture.Tap()
    .runOnJS(true)
    .onStart(() => {
      setTapCountV2((c) => c + 1);
    });

  const tapV3 = useTapGesture({
    runOnJS: true,
    onActivate: () => {
      setTapCountV3((c) => c + 1);
    },
  });

  const [visible, setVisible] = useState(true);
  const [randomViews, setRandomViews] = useState(100);

  const runTest = useCallback(() => {
    setVisible(false);
    setTimeout(() => {
      setRandomViews(Math.random() * 100);
      setTimeout(() => {
        setVisible(true);
      }, 500);
    }, 500);
  }, []);

  return (
    <View style={styles.container}>
      <Text
        style={[
          styles.status,
          { color: tapCountV2 > 0 ? 'green' : 'red', fontSize: 24 },
        ]}>
        v2 Tap count: {tapCountV2}
      </Text>
      <Text
        style={[
          styles.status,
          { color: tapCountV3 > 0 ? 'green' : 'red', fontSize: 24 },
        ]}>
        v3 Tap count: {tapCountV3}
      </Text>
      <Button title="Run Test (Hide→Change→Show)" onPress={runTest} />
      <View
        style={[
          styles.wrapper,
          {
            display: visible ? 'flex' : 'none',
          },
        ]}>
        <View style={styles.row}>
          {Array.from({ length: randomViews }).map((_, i) => (
            <View key={i} style={styles.dot} />
          ))}
        </View>
        <View style={styles.boxRow}>
          <GestureDetector gesture={tapV2}>
            <View style={styles.blueBox}>
              <Text style={styles.blueBoxText}>v2</Text>
            </View>
          </GestureDetector>
          <GestureDetector gesture={tapV3}>
            <View style={styles.greenBox}>
              <Text style={styles.blueBoxText}>v3</Text>
            </View>
          </GestureDetector>
        </View>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#ecf0f1',
    padding: 8,
  },
  status: {
    fontSize: 16,
    fontWeight: 'bold',
    marginBottom: 20,
    textAlign: 'center',
  },
  wrapper: {
    marginTop: 50,
    gap: 20,
    backgroundColor: 'yellow',
  },
  row: {
    flexDirection: 'row',
  },
  dot: {
    width: 2,
    height: 2,
    backgroundColor: 'black',
  },
  boxRow: {
    flexDirection: 'row',
    gap: 20,
  },
  blueBox: {
    height: 50,
    width: 50,
    backgroundColor: 'blue',
    justifyContent: 'center',
    alignItems: 'center',
  },
  greenBox: {
    height: 50,
    width: 50,
    backgroundColor: 'green',
    justifyContent: 'center',
    alignItems: 'center',
  },
  blueBoxText: {
    color: 'white',
    fontWeight: 'bold',
  },
});

```

Steps:

- Tap the box — count increments
- Press "Hide → Change → Show" to trigger display:none + sibling change
+ show
- Tap again — count should still increment (was broken before this fix)
- Repeat multiple cycles to confirm reliability

Author: janicduplessis

packages/react-native-gesture-handler/apple/RNGestureHandler.h

@@ -85,6 +85,7 @@
 @property (nonatomic) BOOL dispatchesReanimatedEvents;
 @property (nonatomic, weak, nullable) RNGHUIView *hostDetectorView;
 @property (nonatomic, nullable, assign) NSNumber *virtualViewTag;
+@property (nonatomic, copy, nullable) NSNumber *viewTag;
 
 - (BOOL)isViewParagraphComponent:(nullable RNGHUIView *)view;
 - (nonnull RNGHUIView *)chooseViewForInteraction:(nonnull UIGestureRecognizer *)recognizer;

packages/react-native-gesture-handler/apple/RNGestureHandler.mm

@@ -262,6 +262,8 @@ - (void)bindToView:(RNGHUIView *)view
 
   [recognizerView addGestureRecognizer:self.recognizer];
   [self bindManualActivationToView:recognizerView];
+
+  self.viewTag = view.reactTag;
 }
 
 - (void)unbindFromView
@@ -271,6 +273,7 @@ - (void)unbindFromView
 
   self.hostDetectorView = nil;
   self.virtualViewTag = nil;
+  self.viewTag = nil;
 
   [self unbindManualActivation];
 }

packages/react-native-gesture-handler/apple/RNGestureHandlerManager.h

@@ -42,4 +42,6 @@
 - (nullable RNGestureHandler *)handlerWithTag:(nonnull NSNumber *)handlerTag;
 
 - (nullable RNGHUIView *)viewForReactTag:(nonnull NSNumber *)reactTag;
+
+- (void)reattachHandlersIfNeeded;
 @end

packages/react-native-gesture-handler/apple/RNGestureHandlerManager.mm

@@ -171,6 +171,21 @@ - (void)attachGestureHandler:(nonnull NSNumber *)handlerTag
   }
 
   [_attachRetryCounter removeObjectForKey:viewTag];
+  [self maybeBindHandler:handlerTag toViewWithTag:viewTag withActionType:actionType withHostDetector:hostDetector];
+}
+
+// Resolves a view tag to its native UIView (including contentView unwrapping),
+// sets reactTag, and binds the gesture handler to it. No-op if the handler is
+// already attached to the correct view.
+- (void)maybeBindHandler:(nonnull NSNumber *)handlerTag
+           toViewWithTag:(nonnull NSNumber *)viewTag
+          withActionType:(RNGestureHandlerActionType)actionType
+        withHostDetector:(nullable RNGHUIView *)hostDetector
+{
+  RNGHUIView *view = [_viewRegistry viewForReactTag:viewTag];
+  if (view == nil || view.superview == nil) {
+    return;
+  }
 
   // I think it should be moved to RNNativeViewHandler, but that would require
   // additional logic for setting contentView.reactTag, this works for now
@@ -181,12 +196,17 @@ - (void)attachGestureHandler:(nonnull NSNumber *)handlerTag
     }
   }
 
+  RNGestureHandler *handler = [_registry handlerWithTag:handlerTag];
+
+  // Already attached to the correct native view, nothing to do.
+  if (handler != nil && handler.recognizer.view == view && handler.actionType == actionType) {
+    return;
+  }
+
   view.reactTag = viewTag; // necessary for RNReanimated eventHash (e.g. "42onGestureHandlerEvent"), also will be
                            // returned as event.target
 
   [_registry attachHandlerWithTag:handlerTag toView:view withActionType:actionType withHostDetector:hostDetector];
-
-  // register view if not already there
   [self registerViewWithGestureRecognizerAttachedIfNeeded:view];
 }
 
@@ -224,6 +244,24 @@ - (id)handlerWithTag:(NSNumber *)handlerTag
   return [_registry handlerWithTag:handlerTag];
 }
 
+- (void)reattachHandlersIfNeeded
+{
+  // Re-bind handlers to their current native views. On Fabric, when a parent view has
+  // display:none and siblings change, the native UIView backing a component may be recycled
+  // and replaced. maybeBindHandler is a no-op if the view is nil or unchanged. This is only
+  // needed for handlers using the old api.
+  for (RNGestureHandler *handler in _registry.handlers.objectEnumerator) {
+    if (handler.viewTag == nil || [handler usesNativeOrVirtualDetector]) {
+      continue;
+    }
+
+    [self maybeBindHandler:handler.tag
+             toViewWithTag:handler.viewTag
+            withActionType:handler.actionType
+          withHostDetector:nil];
+  }
+}
+
 #pragma mark Root Views Management
 
 - (void)registerViewWithGestureRecognizerAttachedIfNeeded:(RNGHUIView *)childView

packages/react-native-gesture-handler/apple/RNGestureHandlerModule.mm

@@ -171,18 +171,21 @@ - (void)flushOperations
 {
   // On the new arch we rely on `flushOperations` for scheduling the operations on the UI thread.
   // On the old arch we rely on `uiManagerWillPerformMounting`
-  if (_operations.count == 0) {
-    return;
-  }
-
   RNGestureHandlerManager *manager = [RNGestureHandlerModule handlerManagerForModuleId:_moduleId];
-  NSArray<GestureHandlerOperation> *operations = _operations;
-  _operations = [NSMutableArray new];
+
+  if (_operations.count > 0) {
+    NSArray<GestureHandlerOperation> *operations = _operations;
+    _operations = [NSMutableArray new];
+
+    [self.viewRegistry_DEPRECATED addUIBlock:^(RCTViewRegistry *viewRegistry) {
+      for (GestureHandlerOperation operation in operations) {
+        operation(manager);
+      }
+    }];
+  }
 
   [self.viewRegistry_DEPRECATED addUIBlock:^(RCTViewRegistry *viewRegistry) {
-    for (GestureHandlerOperation operation in operations) {
-      operation(manager);
-    }
+    [manager reattachHandlersIfNeeded];
   }];
 }
 

packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.h

@@ -21,4 +21,6 @@
 - (void)dropHandlerWithTag:(nonnull NSNumber *)handlerTag;
 - (void)dropAllHandlers;
 
+@property (nonatomic, readonly, nonnull) NSDictionary<NSNumber *, RNGestureHandler *> *handlers;
+
 @end

packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.m

@@ -22,6 +22,11 @@ - (instancetype)init
   return self;
 }
 
+- (NSDictionary<NSNumber *, RNGestureHandler *> *)handlers
+{
+  return _handlers;
+}
+
 - (RNGestureHandler *)handlerWithTag:(NSNumber *)handlerTag
 {
   return _handlers[handlerTag];