Add useTraitHiddenOnIOS feature flag

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<cd8218c8b8588f3317bf63ce8d608548>>
+ * @generated SignedSource<<89627a52825452c8f6c0dd3725f61175>>
  */
 
 /**
@@ -546,6 +546,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun useTraitHiddenOnAndroid(): Boolean = accessor.useTraitHiddenOnAndroid()
 
+  /**
+   * Use Trait::hidden slice-skip on iOS. When false, Hidden subtrees stay mounted and hide via UIView.hidden = YES (the path in UIView+ComponentViewProtocol since 2018) instead of REMOVE + DELETE.
+   */
+  @JvmStatic
+  public fun useTraitHiddenOnIOS(): Boolean = accessor.useTraitHiddenOnIOS()
+
   /**
    * In Bridgeless mode, should legacy NativeModules use the TurboModule system?
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4f9f5c1c46217ed6802abd5f786aac19>>
+ * @generated SignedSource<<e2704fec486263b5f74ab909f9d2f533>>
  */
 
 /**
@@ -106,6 +106,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var useNestedScrollViewAndroidCache: Boolean? = null
   private var useSharedAnimatedBackendCache: Boolean? = null
   private var useTraitHiddenOnAndroidCache: Boolean? = null
+  private var useTraitHiddenOnIOSCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
   private var useUnorderedMapInDifferentiatorCache: Boolean? = null
@@ -887,6 +888,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun useTraitHiddenOnIOS(): Boolean {
+    var cached = useTraitHiddenOnIOSCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.useTraitHiddenOnIOS()
+      useTraitHiddenOnIOSCache = cached
+    }
+    return cached
+  }
+
   override fun useTurboModuleInterop(): Boolean {
     var cached = useTurboModuleInteropCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8916e9f4a938a69ff175c806db9835d4>>
+ * @generated SignedSource<<9a216ce4f720f39e338ba9eb40e3503d>>
  */
 
 /**
@@ -200,6 +200,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun useTraitHiddenOnAndroid(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun useTraitHiddenOnIOS(): Boolean
+
   @DoNotStrip @JvmStatic public external fun useTurboModuleInterop(): Boolean
 
   @DoNotStrip @JvmStatic public external fun useTurboModules(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<d2b14345bf627e35562530912b3aae1f>>
+ * @generated SignedSource<<d047393d9b77ab6bdf610f272ec376cd>>
  */
 
 /**
@@ -195,6 +195,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun useTraitHiddenOnAndroid(): Boolean = false
 
+  override fun useTraitHiddenOnIOS(): Boolean = true
+
   override fun useTurboModuleInterop(): Boolean = false
 
   override fun useTurboModules(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<cbe90c2bf8ba9d34804d97c31edfd31a>>
+ * @generated SignedSource<<e23bcf89e2a15139f6a1511ebb7d6fc8>>
  */
 
 /**
@@ -110,6 +110,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var useNestedScrollViewAndroidCache: Boolean? = null
   private var useSharedAnimatedBackendCache: Boolean? = null
   private var useTraitHiddenOnAndroidCache: Boolean? = null
+  private var useTraitHiddenOnIOSCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
   private var useUnorderedMapInDifferentiatorCache: Boolean? = null
@@ -977,6 +978,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun useTraitHiddenOnIOS(): Boolean {
+    var cached = useTraitHiddenOnIOSCache
+    if (cached == null) {
+      cached = currentProvider.useTraitHiddenOnIOS()
+      accessedFeatureFlags.add("useTraitHiddenOnIOS")
+      useTraitHiddenOnIOSCache = cached
+    }
+    return cached
+  }
+
   override fun useTurboModuleInterop(): Boolean {
     var cached = useTurboModuleInteropCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<536a5156deea17740dd24782bf79feb4>>
+ * @generated SignedSource<<4ba890681ce63a02ddcd443223515323>>
  */
 
 /**
@@ -195,6 +195,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun useTraitHiddenOnAndroid(): Boolean
 
+  @DoNotStrip public fun useTraitHiddenOnIOS(): Boolean
+
   @DoNotStrip public fun useTurboModuleInterop(): Boolean
 
   @DoNotStrip public fun useTurboModules(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<b99eaffc2d11a08a6efe32b2e2732965>>
+ * @generated SignedSource<<592d2f00a3b2ff81533cf74f27068819>>
  */
 
 /**
@@ -555,6 +555,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool useTraitHiddenOnIOS() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useTraitHiddenOnIOS");
+    return method(javaProvider_);
+  }
+
   bool useTurboModuleInterop() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useTurboModuleInterop");
@@ -1025,6 +1031,11 @@ bool JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnAndroid(
   return ReactNativeFeatureFlags::useTraitHiddenOnAndroid();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnIOS(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::useTraitHiddenOnIOS();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::useTurboModuleInterop(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::useTurboModuleInterop();
@@ -1344,6 +1355,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "useTraitHiddenOnAndroid",
         JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnAndroid),
+      makeNativeMethod(
+        "useTraitHiddenOnIOS",
+        JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnIOS),
       makeNativeMethod(
         "useTurboModuleInterop",
         JReactNativeFeatureFlagsCxxInterop::useTurboModuleInterop),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4be32bad403baeca1a28f19ad181c42c>>
+ * @generated SignedSource<<23eef56b233a38a30476600370621264>>
  */
 
 /**
@@ -288,6 +288,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool useTraitHiddenOnAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool useTraitHiddenOnIOS(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool useTurboModuleInterop(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<b55a79c9f84947fa4c12b04f15cfeefb>>
+ * @generated SignedSource<<05ffdb0ed4ce2b2f2eed475127ff170a>>
  */
 
 /**
@@ -370,6 +370,10 @@ bool ReactNativeFeatureFlags::useTraitHiddenOnAndroid() {
   return getAccessor().useTraitHiddenOnAndroid();
 }
 
+bool ReactNativeFeatureFlags::useTraitHiddenOnIOS() {
+  return getAccessor().useTraitHiddenOnIOS();
+}
+
 bool ReactNativeFeatureFlags::useTurboModuleInterop() {
   return getAccessor().useTurboModuleInterop();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8e9b09843bf4a0312b254559a975f612>>
+ * @generated SignedSource<<21d1871f9323c4adc17695dcc141a60d>>
  */
 
 /**
@@ -469,6 +469,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool useTraitHiddenOnAndroid();
 
+  /**
+   * Use Trait::hidden slice-skip on iOS. When false, Hidden subtrees stay mounted and hide via UIView.hidden = YES (the path in UIView+ComponentViewProtocol since 2018) instead of REMOVE + DELETE.
+   */
+  RN_EXPORT static bool useTraitHiddenOnIOS();
+
   /**
    * In Bridgeless mode, should legacy NativeModules use the TurboModule system?
    */

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<ac0901d62505522c1c6f7e251e845871>>
+ * @generated SignedSource<<6c5ecdf9466d74d3a4c66a7bacfc7043>>
  */
 
 /**
@@ -1577,6 +1577,24 @@ bool ReactNativeFeatureFlagsAccessor::useTraitHiddenOnAndroid() {
   return flagValue.value();
 }
 
+bool ReactNativeFeatureFlagsAccessor::useTraitHiddenOnIOS() {
+  auto flagValue = useTraitHiddenOnIOS_.load();
+
+  if (!flagValue.has_value()) {
+    // This block is not exclusive but it is not necessary.
+    // If multiple threads try to initialize the feature flag, we would only
+    // be accessing the provider multiple times but the end state of this
+    // instance and the returned flag value would be the same.
+
+    markFlagAsAccessed(86, "useTraitHiddenOnIOS");
+
+    flagValue = currentProvider_->useTraitHiddenOnIOS();
+    useTraitHiddenOnIOS_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 bool ReactNativeFeatureFlagsAccessor::useTurboModuleInterop() {
   auto flagValue = useTurboModuleInterop_.load();
 
@@ -1586,7 +1604,7 @@ bool ReactNativeFeatureFlagsAccessor::useTurboModuleInterop() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(86, "useTurboModuleInterop");
+    markFlagAsAccessed(87, "useTurboModuleInterop");
 
     flagValue = currentProvider_->useTurboModuleInterop();
     useTurboModuleInterop_ = flagValue;
@@ -1604,7 +1622,7 @@ bool ReactNativeFeatureFlagsAccessor::useTurboModules() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(87, "useTurboModules");
+    markFlagAsAccessed(88, "useTurboModules");
 
     flagValue = currentProvider_->useTurboModules();
     useTurboModules_ = flagValue;
@@ -1622,7 +1640,7 @@ bool ReactNativeFeatureFlagsAccessor::useUnorderedMapInDifferentiator() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(88, "useUnorderedMapInDifferentiator");
+    markFlagAsAccessed(89, "useUnorderedMapInDifferentiator");
 
     flagValue = currentProvider_->useUnorderedMapInDifferentiator();
     useUnorderedMapInDifferentiator_ = flagValue;
@@ -1640,7 +1658,7 @@ double ReactNativeFeatureFlagsAccessor::viewCullingOutsetRatio() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(89, "viewCullingOutsetRatio");
+    markFlagAsAccessed(90, "viewCullingOutsetRatio");
 
     flagValue = currentProvider_->viewCullingOutsetRatio();
     viewCullingOutsetRatio_ = flagValue;
@@ -1658,7 +1676,7 @@ bool ReactNativeFeatureFlagsAccessor::viewTransitionEnabled() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(90, "viewTransitionEnabled");
+    markFlagAsAccessed(91, "viewTransitionEnabled");
 
     flagValue = currentProvider_->viewTransitionEnabled();
     viewTransitionEnabled_ = flagValue;
@@ -1676,7 +1694,7 @@ double ReactNativeFeatureFlagsAccessor::virtualViewPrerenderRatio() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(91, "virtualViewPrerenderRatio");
+    markFlagAsAccessed(92, "virtualViewPrerenderRatio");
 
     flagValue = currentProvider_->virtualViewPrerenderRatio();
     virtualViewPrerenderRatio_ = flagValue;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<9334675799ea378311b8c675ed419b1d>>
+ * @generated SignedSource<<d34324172201668ef16dd273f62a65c7>>
  */
 
 /**
@@ -118,6 +118,7 @@ class ReactNativeFeatureFlagsAccessor {
   bool useNestedScrollViewAndroid();
   bool useSharedAnimatedBackend();
   bool useTraitHiddenOnAndroid();
+  bool useTraitHiddenOnIOS();
   bool useTurboModuleInterop();
   bool useTurboModules();
   bool useUnorderedMapInDifferentiator();
@@ -135,7 +136,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
   bool wasOverridden_;
 
-  std::array<std::atomic<const char*>, 92> accessedFeatureFlags_;
+  std::array<std::atomic<const char*>, 93> accessedFeatureFlags_;
 
   std::atomic<std::optional<bool>> commonTestFlag_;
   std::atomic<std::optional<bool>> cdpInteractionMetricsEnabled_;
@@ -223,6 +224,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::atomic<std::optional<bool>> useNestedScrollViewAndroid_;
   std::atomic<std::optional<bool>> useSharedAnimatedBackend_;
   std::atomic<std::optional<bool>> useTraitHiddenOnAndroid_;
+  std::atomic<std::optional<bool>> useTraitHiddenOnIOS_;
   std::atomic<std::optional<bool>> useTurboModuleInterop_;
   std::atomic<std::optional<bool>> useTurboModules_;
   std::atomic<std::optional<bool>> useUnorderedMapInDifferentiator_;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4a2fd61cbcdb28042f09ccb03c970674>>
+ * @generated SignedSource<<7861725f5c1354b87caba6b7c0e406a7>>
  */
 
 /**
@@ -371,6 +371,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
     return false;
   }
 
+  bool useTraitHiddenOnIOS() override {
+    return true;
+  }
+
   bool useTurboModuleInterop() override {
     return false;
   }