Operations order

ios/REAModule.m

@@ -153,6 +153,7 @@ - (void)addOperationBlock:(AnimatedOperation)operation
 
 - (void)uiManagerWillPerformMounting:(RCTUIManager *)uiManager
 {
+  [_nodesManager maybeFlushUpdateBuffer];
   if (_operations.count == 0) {
     return;
   }

ios/REANodesManager.h

@@ -78,4 +78,6 @@ typedef void (^REAEventHandler)(NSString *eventName, id<RCTEvent> event);
 
 - (void)setValueForNodeID:(nonnull NSNumber *)nodeID value:(nonnull NSNumber *)newValue;
 
+- (void)maybeFlushUpdateBuffer;
+
 @end

ios/REANodesManager.m

@@ -3,6 +3,7 @@
 #import <React/RCTConvert.h>
 
 #import <React/RCTShadowView.h>
+#import <stdatomic.h>
 #import "Nodes/REAAlwaysNode.h"
 #import "Nodes/REABezierNode.h"
 #import "Nodes/REABlockNode.h"
@@ -46,6 +47,17 @@ - (void)runSyncUIUpdatesWithObserver:(id<RCTUIManagerObserver>)observer;
 
 @end
 
+@interface ComponentUpdate : NSObject
+
+@property (nonnull) NSMutableDictionary *props;
+@property (nonnull) NSNumber *viewTag;
+@property (nonnull) NSString *viewName;
+
+@end
+
+@implementation ComponentUpdate
+@end
+
 @implementation RCTUIManager (SyncUpdates)
 
 - (BOOL)hasEnqueuedUICommands
@@ -99,6 +111,9 @@ @implementation REANodesManager {
   BOOL _tryRunBatchUpdatesSynchronously;
   REAEventHandler _eventHandler;
   volatile void (^_mounting)(void);
+  NSMutableDictionary<NSNumber *, ComponentUpdate *> *_componentUpdateBuffer;
+  volatile atomic_bool _shouldFlushUpdateBuffer;
+  NSMutableDictionary<NSNumber *, UIView *> *_viewRegistry;
 }
 
 - (instancetype)initWithModule:(REAModule *)reanimatedModule uiManager:(RCTUIManager *)uiManager
@@ -113,6 +128,9 @@ - (instancetype)initWithModule:(REAModule *)reanimatedModule uiManager:(RCTUIMan
     _wantRunUpdates = NO;
     _onAnimationCallbacks = [NSMutableArray new];
     _operationsInBatch = [NSMutableArray new];
+    _componentUpdateBuffer = [NSMutableDictionary new];
+    _viewRegistry = [_uiManager valueForKey:@"_viewRegistry"];
+    _shouldFlushUpdateBuffer = false;
   }
 
   _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(onAnimationFrame:)];
@@ -492,6 +510,11 @@ - (void)configureProps:(NSSet<NSString *> *)nativeProps uiProps:(NSSet<NSString
   _nativeProps = nativeProps;
 }
 
+- (BOOL)isNotNativeViewFullyMounted:(NSNumber *)viewTag
+{
+  return _viewRegistry[viewTag].superview == nil;
+}
+
 - (void)setValueForNodeID:(nonnull NSNumber *)nodeID value:(nonnull NSNumber *)newValue
 {
   RCTAssertParam(nodeID);
@@ -506,6 +529,24 @@ - (void)updateProps:(nonnull NSDictionary *)props
       ofViewWithTag:(nonnull NSNumber *)viewTag
            withName:(nonnull NSString *)viewName
 {
+  ComponentUpdate *lastSnapshot = _componentUpdateBuffer[viewTag];
+  if ([self isNotNativeViewFullyMounted:viewTag] || lastSnapshot != nil) {
+    if (lastSnapshot == nil) {
+      ComponentUpdate *propsSnapshot = [ComponentUpdate new];
+      propsSnapshot.props = [props mutableCopy];
+      propsSnapshot.viewTag = viewTag;
+      propsSnapshot.viewName = viewName;
+      _componentUpdateBuffer[viewTag] = propsSnapshot;
+      atomic_store(&_shouldFlushUpdateBuffer, true);
+    } else {
+      NSMutableDictionary *lastProps = lastSnapshot.props;
+      for (NSString *key in props) {
+        [lastProps setValue:props[key] forKey:key];
+      }
+    }
+    return;
+  }
+
   // TODO: refactor PropsNode to also use this function
   NSMutableDictionary *uiProps = [NSMutableDictionary new];
   NSMutableDictionary *nativeProps = [NSMutableDictionary new];
@@ -553,4 +594,34 @@ - (NSString *)obtainProp:(nonnull NSNumber *)viewTag propName:(nonnull NSString
   return result;
 }
 
+- (void)maybeFlushUpdateBuffer
+{
+  RCTAssertUIManagerQueue();
+  bool shouldFlushUpdateBuffer = atomic_load(&_shouldFlushUpdateBuffer);
+  if (!shouldFlushUpdateBuffer) {
+    return;
+  }
+
+  __weak typeof(self) weakSelf = self;
+  [_uiManager addUIBlock:^(__unused RCTUIManager *manager, __unused NSDictionary<NSNumber *, UIView *> *viewRegistry) {
+    __typeof__(self) strongSelf = weakSelf;
+    if (strongSelf == nil) {
+      return;
+    }
+    atomic_store(&strongSelf->_shouldFlushUpdateBuffer, false);
+    NSMutableDictionary *componentUpdateBuffer = [strongSelf->_componentUpdateBuffer copy];
+    strongSelf->_componentUpdateBuffer = [NSMutableDictionary new];
+    for (NSNumber *tag in componentUpdateBuffer) {
+      ComponentUpdate *componentUpdate = componentUpdateBuffer[tag];
+      if (componentUpdate == Nil) {
+        continue;
+      }
+      [strongSelf updateProps:componentUpdate.props
+                ofViewWithTag:componentUpdate.viewTag
+                     withName:componentUpdate.viewName];
+    }
+    [strongSelf performOperations];
+  }];
+}
+
 @end