fix a node background color in non layer baked mode.

Source/ASDisplayNode.mm

@@ -447,14 +447,13 @@ - (void)asyncTraitCollectionDidChangeWithPreviousTraitCollection:(ASPrimitiveTra
       ASCornerRoundingType cornerRoundingType = _cornerRoundingType;
       UIColor *backgroundColor = _backgroundColor;
       if (_loaded(self)) {
-        if (self.isLayerBacked) {
+        CGColorRef cgBackgroundColor = backgroundColor.CGColor;
+        if (!CGColorEqualToColor(_layer.backgroundColor, cgBackgroundColor)) {
           // Background colors do not dynamically update for layer backed nodes since they utilize CGColorRef
-          // instead of UIColor. We utilize the _backgroundColor instance variable to track the full dynamic color
+          // instead of UIColor. Non layer backed node also receive color to the layer (see [_ASPendingState -applyToView:withSpecialPropertiesHandling:]).
+          // We utilize the _backgroundColor instance variable to track the full dynamic color
           // and apply any changes here when trait collection updates occur.
-          CGColorRef cgBackgroundColor = backgroundColor.CGColor;
-          if (!CGColorEqualToColor(_layer.backgroundColor, cgBackgroundColor)) {
-            _layer.backgroundColor = cgBackgroundColor;
-          }
+          _layer.backgroundColor = cgBackgroundColor;
         }
         // If we have clipping corners, re-render the clipping corner layer upon user interface style change
         if (cornerRoundingType == ASCornerRoundingTypeClipping && cornerRadius > 0.0f) {

Source/Private/_ASPendingState.mm

@@ -1334,7 +1334,7 @@ + (_ASPendingState *)pendingViewStateFromView:(UIView *)view
   pendingState.contentsScale = layer.contentsScale;
   pendingState.rasterizationScale = layer.rasterizationScale;
   pendingState.clipsToBounds = view.clipsToBounds;
-  pendingState.backgroundColor = [UIColor colorWithCGColor:layer.backgroundColor];
+  pendingState.backgroundColor = view.backgroundColor;
   pendingState.tintColor = view.tintColor;
   pendingState.opaque = layer.opaque;
   pendingState.hidden = view.hidden;

Tests/ASDisplayNodeSnapshotTests.mm

@@ -16,6 +16,13 @@ @interface ASDisplayNodeSnapshotTests : ASSnapshotTestCase
 
 @implementation ASDisplayNodeSnapshotTests
 
+- (void)setUp {
+  [super setUp];
+  ASConfiguration *config = [ASConfiguration new];
+  config.experimentalFeatures = ASExperimentalTraitCollectionDidChangeWithPreviousCollection;
+  [ASConfigurationManager test_resetWithConfiguration:config];
+}
+
 - (void)testBasicHierarchySnapshotTesting
 {
   ASDisplayNode *node = [[ASDisplayNode alloc] init];
@@ -112,10 +119,6 @@ - (void)testClippingCornerRounding
 - (void)testUserInterfaceStyleSnapshotTesting
 {
   if (@available(iOS 13.0, *)) {
-    ASConfiguration *config = [ASConfiguration new];
-    config.experimentalFeatures = ASExperimentalTraitCollectionDidChangeWithPreviousCollection;
-    [ASConfigurationManager test_resetWithConfiguration:config];
-
     ASDisplayNode *node = [[ASDisplayNode alloc] init];
     [node setLayerBacked:YES];
 
@@ -134,6 +137,45 @@ - (void)testUserInterfaceStyleSnapshotTesting
   }
 }
 
+- (void)testBackgroundDynamicColor {
+  if (@available(iOS 13.0, *)) {
+    ASDisplayNode *node = [[ASImageNode alloc] init];
+    node.backgroundColor = [UIColor systemGray6Color];
+    auto bounds = CGRectMake(0, 0, 100, 100);
+    node.frame = bounds;
+
+    UITraitCollection *tcLight = [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleLight];
+    [tcLight performAsCurrentTraitCollection: ^{
+      ASSnapshotVerifyNode(node, @"light");
+    }];
+
+    UITraitCollection *tcDark = [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleDark];
+    [tcDark performAsCurrentTraitCollection: ^{
+      ASSnapshotVerifyNode(node, @"dark");
+    }];
+  }
+}
+
+- (void)testBackgroundDynamicColorLayerBacked {
+  if (@available(iOS 13.0, *)) {
+    ASDisplayNode *node = [[ASImageNode alloc] init];
+    node.backgroundColor = [UIColor systemGray6Color];
+    node.layerBacked = YES;
+    auto bounds = CGRectMake(0, 0, 100, 100);
+    node.frame = bounds;
+
+    UITraitCollection *tcLight = [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleLight];
+    [tcLight performAsCurrentTraitCollection: ^{
+      ASSnapshotVerifyNode(node, @"light");
+    }];
+
+    UITraitCollection *tcDark = [UITraitCollection traitCollectionWithUserInterfaceStyle:UIUserInterfaceStyleDark];
+    [tcDark performAsCurrentTraitCollection: ^{
+      ASSnapshotVerifyNode(node, @"dark");
+    }];
+  }
+}
+
 #endif // #if AS_AT_LEAST_IOS13
 
 @end