use RCTUnsafeExecuteOnMainQueueSync

Author: alanjhughes

packages/react-native/React/CoreModules/RCTAppearance.mm

@@ -39,15 +39,10 @@ void RCTOverrideAppearancePreference(NSString *const colorSchemeOverride)
 static UITraitCollection *getKeyWindowTraitCollection()
 {
   __block UITraitCollection *traitCollection = nil;
-  if (RCTIsMainQueue()) {
-    return RCTSharedApplication().delegate.window.traitCollection;
-  } else {
-    __block UITraitCollection* traitCollection = nil;
-    dispatch_sync(dispatch_get_main_queue(), ^{
-      traitCollection = RCTSharedApplication().delegate.window.traitCollection;
-    });
-    return traitCollection;
-  }
+  RCTUnsafeExecuteOnMainQueueSync(^{
+    traitCollection = RCTSharedApplication().delegate.window.traitCollection;
+  });
+  return traitCollection;
 }
 
 NSString *RCTColorSchemePreference(UITraitCollection *traitCollection)