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

[janicduplessis]

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:

function DisplayNoneTest() {
  const visible = useSharedValue(true);
  const [views, setViews] = useState(100);
  const [count, setCount] = useState(0);

  const tap = Gesture.Tap().runOnJS(true).onStart(() => setCount(c => c + 1));

  const style = useAnimatedStyle(() => ({
    display: visible.value ? 'flex' : 'none',
  }));

  const runTest = () => {
    visible.value = false;
    setTimeout(() => {
      setViews(Math.random() * 100); // trigger sibling change while hidden
      setTimeout(() => { visible.value = true; }, 500);
    }, 500);
  };

  return (
    <View>
      <Text>Tap count: {count}</Text>
      <Button title="Hide → Change → Show" onPress={runTest} />
      <Animated.View style={style}>
        {Array.from({ length: views }).map((_, i) => <View key={i} />)}
        <GestureDetector gesture={tap}>
          <View><Text>TAP</Text></View>
        </GestureDetector>
      </Animated.View>
    </View>
  );
}

Steps:

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

[Copilot]

Pull request overview

Fixes GestureDetector becoming unresponsive on Fabric after a display: 'none' hide/show cycle by reattaching gesture handlers when Fabric recycles underlying UIView instances.

Changes:

• Track the React view tag (viewTag) each handler is bound to and clear it on unbind
• Add a reattach pass (reattachHandlersIfNeeded) executed after each UI operations flush
• Add a basic-example repro screen for the display:none recycling scenario

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.m	Refactors registry implementation to support exposing handler collection
packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.h	Exposes registry handlers collection for reattach iteration
packages/react-native-gesture-handler/apple/RNGestureHandlerModule.mm	Ensures UI block runs to reattach handlers after flush
packages/react-native-gesture-handler/apple/RNGestureHandlerManager.mm	Adds helper for binding + reattach pass over registered handlers
packages/react-native-gesture-handler/apple/RNGestureHandlerManager.h	Exposes reattachHandlersIfNeeded on manager
packages/react-native-gesture-handler/apple/RNGestureHandler.mm	Stores viewTag when binding and clears it on unbind
packages/react-native-gesture-handler/apple/RNGestureHandler.h	Adds viewTag property to handler
apps/basic-example/src/DisplayNone.tsx	Adds a repro/testing screen for the Fabric display:none issue
apps/basic-example/src/App.tsx	Registers the new example screen in the example list

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

This enumerates _registry.handlers while calling maybeBindHandler, which in turn calls into registry attach logic (attachHandlerWithTag:...). If the registry mutates its handlers dictionary as part of (re)attach, this risks a “mutated while being enumerated” crash. Safer approach: iterate over a snapshot (e.g., _registry.handlers.allValues captured into an array before the loop, or iterate over a copied dictionary’s values).

[janicduplessis]

This is safe because attachHandlerWithTag:toView:withActionType:withHostDetector: in the registry only mutates existing entries (calls unbindFromView/bindToView on a handler that's already in the dictionary). It never adds or removes keys from _handlers, so the dictionary is not structurally mutated during enumeration.

[janicduplessis]

Using objectEnumerator here instead of allValues to avoid allocating a temporary array on every flush.