Overwrite betterHitTest in RCTScrollViewComponentView instead of changing layout metrics of the container view (facebook#50027)

Summary:
Pull Request resolved: facebook#50027

Changelog: [IOS][CHANGED] - Overwrite betterHitTest in RCTScrollViewComponentView instead of changing layout metrics of the container view

## Summary:

In facebook#49855 I changed the container view of `RCTScrollViewComponentView` to be `RCTViewComponentView` instead of `UIView` so the touches would bass through its `betterHitTest` implementation (along with udating its layout metrics so the right path in the function is chosen). This resulted in some issues and the alternative approach of customizing the hit testing of the ScrollView itself might be a better approach.

This PR changes overwrites the `betterHitTest` method in a way that the `containerView` is entirely skipped during hit testing, instead forwarding the call to its children. This way, it won't prevent touches outside its frame from being delivered to children that extend out of the frame.

Reviewed By: cipolleschi

Differential Revision: D71187882

fbshipit-source-id: 9d0c79048f389b9bee37dea1e59226b54ddbe6f2

Author: j-piasecki

packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -89,7 +89,6 @@ @interface RCTScrollViewComponentView () <
 
 @implementation RCTScrollViewComponentView {
   ScrollViewShadowNode::ConcreteState::Shared _state;
-  LayoutMetrics _lastContentContainerLayoutMetrics;
   CGSize _contentSize;
   NSTimeInterval _lastScrollEventDispatchTime;
   NSTimeInterval _scrollEventThrottle;
@@ -133,7 +132,7 @@ - (instancetype)initWithFrame:(CGRect)frame
     _automaticallyAdjustKeyboardInsets = NO;
     [self addSubview:_scrollView];
 
-    _containerView = [[RCTViewComponentView alloc] initWithFrame:CGRectZero];
+    _containerView = [[UIView alloc] initWithFrame:CGRectZero];
     [_scrollView addSubview:_containerView];
 
     [self.scrollViewDelegateSplitter addDelegate:self];
@@ -469,17 +468,44 @@ - (void)updateState:(const State::Shared &)state oldState:(const State::Shared &
   }
 
   _contentSize = contentSize;
-  LayoutMetrics newContentContainerLayoutMetrics = LayoutMetrics{
-      .frame = {.origin = data.contentBoundingRect.origin, .size = data.getContentSize()}, .overflowInset = {.top = 1}};
-  [_containerView updateLayoutMetrics:newContentContainerLayoutMetrics
-                     oldLayoutMetrics:_lastContentContainerLayoutMetrics];
-  _lastContentContainerLayoutMetrics = newContentContainerLayoutMetrics;
+  _containerView.frame = CGRect{RCTCGPointFromPoint(data.contentBoundingRect.origin), contentSize};
 
   [self _preserveContentOffsetIfNeededWithBlock:^{
     self->_scrollView.contentSize = contentSize;
   }];
 }
 
+- (UIView *)betterHitTest:(CGPoint)point withEvent:(UIEvent *)event
+{
+  // This is the same algorithm as in the RCTViewComponentView with the exception of
+  // skipping the immediate child (_containerView) and checking grandchildren instead.
+  // This prevents issues with touches outside of _containerView being ignored even
+  // if they are within the bounds of the _containerView's children.
+
+  if (!self.userInteractionEnabled || self.hidden || self.alpha < 0.01) {
+    return nil;
+  }
+
+  BOOL isPointInside = [self pointInside:point withEvent:event];
+
+  BOOL clipsToBounds = _containerView.clipsToBounds;
+
+  clipsToBounds = clipsToBounds || _layoutMetrics.overflowInset == EdgeInsets{};
+
+  if (clipsToBounds && !isPointInside) {
+    return nil;
+  }
+
+  for (UIView *subview in [_containerView.subviews reverseObjectEnumerator]) {
+    UIView *hitView = [subview hitTest:[subview convertPoint:point fromView:self] withEvent:event];
+    if (hitView) {
+      return hitView;
+    }
+  }
+
+  return isPointInside ? self : nil;
+}
+
 /*
  * Disables programmatical changing of ScrollView's `contentOffset` if a touch gesture is in progress.
  */

packages/react-native/React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.h

@@ -74,6 +74,7 @@ NS_ASSUME_NONNULL_BEGIN
            oldLayoutMetrics:(const facebook::react::LayoutMetrics &)oldLayoutMetrics NS_REQUIRES_SUPER;
 - (void)finalizeUpdates:(RNComponentViewUpdateMask)updateMask NS_REQUIRES_SUPER;
 - (void)prepareForRecycle NS_REQUIRES_SUPER;
+- (UIView *)betterHitTest:(CGPoint)point withEvent:(UIEvent *)event;
 
 /*
  * This is a fragment of temporary workaround that we need only temporary and will get rid of soon.