Fix potential retain cycles in Animated iOS

Summary:
Fixes potential retain cycles detected by an internal fb tool.

```
First:

__NSDictionaryM
-> RCTPropsAnimatedNode
-> _parentNodes -> __NSDictionaryM
-> RCTStyleAnimatedNode
-> _childNodes -> __NSDictionaryM

Second:

RCTScrollView
-> _eventDispatcher -> RCTEventDispatcher
-> _observers -> __NSArrayM
-> RCTNativeAnimatedModule
-> _nodesManager -> RCTNativeAnimatedNodesManager
-> _uiManager -> RCTUIManager
-> _viewRegistry -> __NSDictionaryM
-> RCTScrollView
```

First fix:
Use weak map for parent and child nodes, strong refs are managed by RCTNativeAnimatedNodesManager

Second fix:
Make RCTEventDispatcher observers a weak array and make sure we don't keep strong refs to UIManager in RCTNativeAnimatedNodesManager and RCTPropsAnimatedNode.

Tested that native animations still work in UIExplorer

[IOS] [BUGFIX] [NativeAnimated] - Fix potential retain cycles in Animated iOS
Closes https://github.com/facebook/react-native/pull/16506

Differential Revision: D6126400

Pulled By: shergin

fbshipit-source-id: 1ac5083f8ab79a806305edc23ae4796ed428f78b

Libraries/NativeAnimation/Nodes/RCTAdditionAnimatedNode.m

@@ -16,8 +16,8 @@
   [super performUpdate];
   NSArray<NSNumber *> *inputNodes = self.config[@"input"];
   if (inputNodes.count > 1) {
-    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[0]];
-    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[1]];
+    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[0]];
+    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[1]];
     if ([parent1 isKindOfClass:[RCTValueAnimatedNode class]] &&
         [parent2 isKindOfClass:[RCTValueAnimatedNode class]]) {
       self.value = parent1.value + parent2.value;

Libraries/NativeAnimation/Nodes/RCTAnimatedNode.h

@@ -17,8 +17,8 @@
 @property (nonatomic, readonly) NSNumber *nodeTag;
 @property (nonatomic, copy, readonly) NSDictionary<NSString *, id> *config;
 
-@property (nonatomic, copy, readonly) NSDictionary<NSNumber *, RCTAnimatedNode *> *childNodes;
-@property (nonatomic, copy, readonly) NSDictionary<NSNumber *, RCTAnimatedNode *> *parentNodes;
+@property (nonatomic, copy, readonly) NSMapTable<NSNumber *, RCTAnimatedNode *> *childNodes;
+@property (nonatomic, copy, readonly) NSMapTable<NSNumber *, RCTAnimatedNode *> *parentNodes;
 
 @property (nonatomic, readonly) BOOL needsUpdate;
 

Libraries/NativeAnimation/Nodes/RCTAnimatedNode.m

@@ -13,8 +13,8 @@
 
 @implementation RCTAnimatedNode
 {
-  NSMutableDictionary<NSNumber *, RCTAnimatedNode *> *_childNodes;
-  NSMutableDictionary<NSNumber *, RCTAnimatedNode *> *_parentNodes;
+  NSMapTable<NSNumber *, RCTAnimatedNode *> *_childNodes;
+  NSMapTable<NSNumber *, RCTAnimatedNode *> *_parentNodes;
 }
 
 - (instancetype)initWithTag:(NSNumber *)tag
@@ -29,12 +29,12 @@
 
 RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
-- (NSDictionary<NSNumber *, RCTAnimatedNode *> *)childNodes
+- (NSMapTable<NSNumber *, RCTAnimatedNode *> *)childNodes
 {
   return _childNodes;
 }
 
-- (NSDictionary<NSNumber *, RCTAnimatedNode *> *)parentNodes
+- (NSMapTable<NSNumber *, RCTAnimatedNode *> *)parentNodes
 {
   return _parentNodes;
 }
@@ -42,10 +42,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 - (void)addChild:(RCTAnimatedNode *)child
 {
   if (!_childNodes) {
-    _childNodes = [NSMutableDictionary new];
+    _childNodes = [NSMapTable strongToWeakObjectsMapTable];
   }
   if (child) {
-    _childNodes[child.nodeTag] = child;
+    [_childNodes setObject:child forKey:child.nodeTag];
     [child onAttachedToNode:self];
   }
 }
@@ -64,10 +64,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 - (void)onAttachedToNode:(RCTAnimatedNode *)parent
 {
   if (!_parentNodes) {
-    _parentNodes = [NSMutableDictionary new];
+    _parentNodes = [NSMapTable strongToWeakObjectsMapTable];
   }
   if (parent) {
-    _parentNodes[parent.nodeTag] = parent;
+    [_parentNodes setObject:parent forKey:parent.nodeTag];
   }
 }
 
@@ -83,10 +83,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 - (void)detachNode
 {
-  for (RCTAnimatedNode *parent in _parentNodes.allValues) {
+  for (RCTAnimatedNode *parent in _parentNodes.objectEnumerator) {
     [parent removeChild:self];
   }
-  for (RCTAnimatedNode *child in _childNodes.allValues) {
+  for (RCTAnimatedNode *child in _childNodes.objectEnumerator) {
     [self removeChild:child];
   }
 }
@@ -94,7 +94,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 - (void)setNeedsUpdate
 {
   _needsUpdate = YES;
-  for (RCTAnimatedNode *child in _childNodes.allValues) {
+  for (RCTAnimatedNode *child in _childNodes.objectEnumerator) {
     [child setNeedsUpdate];
   }
 }
@@ -102,7 +102,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 - (void)updateNodeIfNecessary
 {
   if (_needsUpdate) {
-    for (RCTAnimatedNode *parent in _parentNodes.allValues) {
+    for (RCTAnimatedNode *parent in _parentNodes.objectEnumerator) {
       [parent updateNodeIfNecessary];
     }
     [self performUpdate];

Libraries/NativeAnimation/Nodes/RCTDiffClampAnimatedNode.m

@@ -51,7 +51,7 @@
 
 - (CGFloat)inputNodeValue
 {
-  RCTValueAnimatedNode *inputNode = (RCTValueAnimatedNode *)self.parentNodes[_inputNodeTag];
+  RCTValueAnimatedNode *inputNode = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:_inputNodeTag];
   if (![inputNode isKindOfClass:[RCTValueAnimatedNode class]]) {
     RCTLogError(@"Illegal node ID set as an input for Animated.DiffClamp node");
     return 0;

Libraries/NativeAnimation/Nodes/RCTDivisionAnimatedNode.m

@@ -19,8 +19,8 @@
 
   NSArray<NSNumber *> *inputNodes = self.config[@"input"];
   if (inputNodes.count > 1) {
-    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[0]];
-    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[1]];
+    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[0]];
+    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[1]];
     if ([parent1 isKindOfClass:[RCTValueAnimatedNode class]] &&
         [parent2 isKindOfClass:[RCTValueAnimatedNode class]]) {
       if (parent2.value == 0) {

Libraries/NativeAnimation/Nodes/RCTModuloAnimatedNode.m

@@ -16,7 +16,7 @@
   [super performUpdate];
   NSNumber *inputNode = self.config[@"input"];
   NSNumber *modulus = self.config[@"modulus"];
-  RCTValueAnimatedNode *parent = (RCTValueAnimatedNode *)self.parentNodes[inputNode];
+  RCTValueAnimatedNode *parent = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNode];
   self.value = fmodf(parent.value, modulus.floatValue);
 }
 

Libraries/NativeAnimation/Nodes/RCTMultiplicationAnimatedNode.m

@@ -17,8 +17,8 @@
 
   NSArray<NSNumber *> *inputNodes = self.config[@"input"];
   if (inputNodes.count > 1) {
-    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[0]];
-    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[1]];
+    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[0]];
+    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)[self.parentNodes objectForKey:inputNodes[1]];
     if ([parent1 isKindOfClass:[RCTValueAnimatedNode class]] &&
         [parent2 isKindOfClass:[RCTValueAnimatedNode class]]) {
       self.value = parent1.value * parent2.value;

Libraries/NativeAnimation/Nodes/RCTPropsAnimatedNode.m

@@ -20,7 +20,7 @@
 {
   NSNumber *_connectedViewTag;
   NSString *_connectedViewName;
-  RCTUIManager *_uiManager;
+  __weak RCTUIManager *_uiManager;
   NSMutableDictionary<NSString *, NSObject *> *_propsDictionary;
 }
 
@@ -85,18 +85,18 @@
   if (!_connectedViewTag) {
     return;
   }
-
-  [self.parentNodes enumerateKeysAndObjectsUsingBlock:^(NSNumber *_Nonnull parentTag, RCTAnimatedNode *_Nonnull parentNode, BOOL *_Nonnull stop) {
-
+  
+  for (NSNumber *parentTag in self.parentNodes.keyEnumerator) {
+    RCTAnimatedNode *parentNode = [self.parentNodes objectForKey:parentTag];
     if ([parentNode isKindOfClass:[RCTStyleAnimatedNode class]]) {
       [self->_propsDictionary addEntriesFromDictionary:[(RCTStyleAnimatedNode *)parentNode propsDictionary]];
-
+      
     } else if ([parentNode isKindOfClass:[RCTValueAnimatedNode class]]) {
       NSString *property = [self propertyNameForParentTag:parentTag];
       CGFloat value = [(RCTValueAnimatedNode *)parentNode value];
       self->_propsDictionary[property] = @(value);
     }
-  }];
+  }
 
   if (_propsDictionary.count) {
     [_uiManager synchronouslyUpdateViewOnUIThread:_connectedViewTag

Libraries/NativeAnimation/Nodes/RCTStyleAnimatedNode.m

@@ -37,7 +37,7 @@
 
   NSDictionary<NSString *, NSNumber *> *style = self.config[@"style"];
   [style enumerateKeysAndObjectsUsingBlock:^(NSString *property, NSNumber *nodeTag, __unused BOOL *stop) {
-    RCTAnimatedNode *node = self.parentNodes[nodeTag];
+    RCTAnimatedNode *node = [self.parentNodes objectForKey:nodeTag];
     if (node) {
       if ([node isKindOfClass:[RCTValueAnimatedNode class]]) {
         RCTValueAnimatedNode *parentNode = (RCTValueAnimatedNode *)node;

Libraries/NativeAnimation/Nodes/RCTTransformAnimatedNode.m

@@ -41,7 +41,7 @@
     NSNumber *value;
     if ([type isEqualToString: @"animated"]) {
       NSNumber *nodeTag = transformConfig[@"nodeTag"];
-      RCTAnimatedNode *node = self.parentNodes[nodeTag];
+      RCTAnimatedNode *node = [self.parentNodes objectForKey:nodeTag];
       if (![node isKindOfClass:[RCTValueAnimatedNode class]]) {
         continue;
       }

Libraries/NativeAnimation/RCTNativeAnimatedNodesManager.m

@@ -30,7 +30,7 @@
 
 @implementation RCTNativeAnimatedNodesManager
 {
-  RCTUIManager *_uiManager;
+  __weak RCTUIManager *_uiManager;
   NSMutableDictionary<NSNumber *, RCTAnimatedNode *> *_animationNodes;
   // Mapping of a view tag and an event name to a list of event animation drivers. 99% of the time
   // there will be only one driver per mapping so all code code should be optimized around that.

React/Base/RCTEventDispatcher.m

@@ -46,7 +46,7 @@ static NSNumber *RCTGetEventID(id<RCTEvent> event)
   // This array contains ids of events in order they come in, so we can emit them to JS in the exact same order.
   NSMutableArray<NSNumber *> *_eventQueue;
   BOOL _eventsDispatchScheduled;
-  NSMutableArray<id<RCTEventDispatcherObserver>> *_observers;
+  NSHashTable<id<RCTEventDispatcherObserver>> *_observers;
   NSLock *_observersLock;
 }
 
@@ -61,7 +61,7 @@ RCT_EXPORT_MODULE()
   _eventQueue = [NSMutableArray new];
   _eventQueueLock = [NSLock new];
   _eventsDispatchScheduled = NO;
-  _observers = [NSMutableArray new];
+  _observers = [NSHashTable weakObjectsHashTable];
   _observersLock = [NSLock new];
 }