fix calling CALayer out of the main thread

Source/ASDisplayNode.mm

@@ -438,36 +438,43 @@ - (void)onDidLoad:(ASDisplayNodeDidLoadBlock)body
 - (void)asyncTraitCollectionDidChangeWithPreviousTraitCollection:(ASPrimitiveTraitCollection)previousTraitCollection
 {
   if (@available(iOS 13.0, *)) {
+    // When changing between light and dark mode, often the entire node needs to re-render.
+    // This change doesn't happen frequently so it's fairly safe to render nodes again
     __instanceLock__.lock();
-    if (self.primitiveTraitCollection.userInterfaceStyle != previousTraitCollection.userInterfaceStyle) {
-      // When changing between light and dark mode, often the entire node needs to re-render.
-      // This change doesn't happen frequently so it's fairly safe to render nodes again
-      BOOL needsClippingCornerUpdate = NO;
-      CGFloat cornerRadius = _cornerRadius;
-      ASCornerRoundingType cornerRoundingType = _cornerRoundingType;
-      UIColor *backgroundColor = _backgroundColor;
-      if (_loaded(self)) {
-        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. 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.
-          _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) {
-          needsClippingCornerUpdate = YES;
-        }
-      }
-      __instanceLock__.unlock();
-      if (needsClippingCornerUpdate) {
-        [self _updateClipCornerLayerContentsWithRadius:cornerRadius backgroundColor:backgroundColor];
+    BOOL loaded = _loaded(self);
+    ASPrimitiveTraitCollection primitiveTraitCollection = _primitiveTraitCollection;
+    __instanceLock__.unlock();
+    if (primitiveTraitCollection.userInterfaceStyle != previousTraitCollection.userInterfaceStyle) {
+      if (loaded) {
+        // we need to run that on main thread, cause accessing CALayer properties.
+        // It seems than in iOS 13 sometimes it causes deadlock.
+        ASPerformBlockOnMainThread(^{
+          __instanceLock__.lock();
+          CGFloat cornerRadius = _cornerRadius;
+          ASCornerRoundingType cornerRoundingType = _cornerRoundingType;
+          UIColor *backgroundColor = _backgroundColor;
+          ASPrimitiveTraitCollection primitiveTraitCollection = _primitiveTraitCollection;
+          __instanceLock__.unlock();
+          UITraitCollection *traitCollection = ASPrimitiveTraitCollectionToUITraitCollection(primitiveTraitCollection);
+          UIColor *resolvedBackgroundColor = [backgroundColor resolvedColorWithTraitCollection:traitCollection];
+          CGColorRef cgBackgroundColor = resolvedBackgroundColor.CGColor;
+          if (!CGColorEqualToColor(_layer.backgroundColor, cgBackgroundColor)) {
+            // Background colors do not dynamically update for layer backed nodes since they utilize CGColorRef
+            // 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.
+            _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) {
+            [self _updateClipCornerLayerContentsWithRadius:cornerRadius backgroundColor:backgroundColor];
+          }
+
+          [self setNeedsDisplay];
+        });
       }
-      [self setNeedsDisplay];
-      return;
     }
-    __instanceLock__.unlock();
   }
 }