Merge pull request #1693 from rcancro/traitUpdate

[ASTraitCollection] Bug fixing/LayoutSpec propagation

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -589,8 +589,8 @@
 		E55D86331CA8A14000A0C26F /* ASLayoutable.mm in Sources */ = {isa = PBXBuildFile; fileRef = E55D86311CA8A14000A0C26F /* ASLayoutable.mm */; };
 		E5711A2B1C840C81009619D4 /* ASIndexedNodeContext.h in Headers */ = {isa = PBXBuildFile; fileRef = E5711A2A1C840C81009619D4 /* ASIndexedNodeContext.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		E5711A2C1C840C81009619D4 /* ASIndexedNodeContext.h in Headers */ = {isa = PBXBuildFile; fileRef = E5711A2A1C840C81009619D4 /* ASIndexedNodeContext.h */; };
-		E5711A2E1C840C96009619D4 /* ASIndexedNodeContext.m in Sources */ = {isa = PBXBuildFile; fileRef = E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.m */; };
+		E5711A2E1C840C96009619D4 /* ASIndexedNodeContext.mm in Sources */ = {isa = PBXBuildFile; fileRef = E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.mm */; };
-		E5711A301C840C96009619D4 /* ASIndexedNodeContext.m in Sources */ = {isa = PBXBuildFile; fileRef = E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.m */; };
+		E5711A301C840C96009619D4 /* ASIndexedNodeContext.mm in Sources */ = {isa = PBXBuildFile; fileRef = E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.mm */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -955,7 +955,7 @@
 		E52405B41C8FEF16004DC8E7 /* ASLayoutTransition.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASLayoutTransition.h; sourceTree = "<group>"; };
 		E55D86311CA8A14000A0C26F /* ASLayoutable.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = ASLayoutable.mm; path = AsyncDisplayKit/Layout/ASLayoutable.mm; sourceTree = "<group>"; };
 		E5711A2A1C840C81009619D4 /* ASIndexedNodeContext.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASIndexedNodeContext.h; sourceTree = "<group>"; };
-		E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASIndexedNodeContext.m; sourceTree = "<group>"; };
+		E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASIndexedNodeContext.mm; sourceTree = "<group>"; };
 		EFA731F0396842FF8AB635EE /* libPods-AsyncDisplayKitTests.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-AsyncDisplayKitTests.a"; sourceTree = BUILT_PRODUCTS_DIR; };
 		FB07EABBCF28656C6297BC2D /* Pods-AsyncDisplayKitTests.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-AsyncDisplayKitTests.debug.xcconfig"; path = "Pods/Target Support Files/Pods-AsyncDisplayKitTests/Pods-AsyncDisplayKitTests.debug.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
@@ -1417,7 +1417,7 @@
 				AC026B671BD57D6F00BBC17E /* ASChangeSetDataController.h */,
 				AC026B681BD57D6F00BBC17E /* ASChangeSetDataController.m */,
 				E5711A2A1C840C81009619D4 /* ASIndexedNodeContext.h */,
-				E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.m */,
+				E5711A2D1C840C96009619D4 /* ASIndexedNodeContext.mm */,
 			);
 			name = "Data Controller";
 			sourceTree = "<group>";
@@ -2114,7 +2114,7 @@
 				205F0E121B371BD7007741D0 /* ASScrollDirection.m in Sources */,
 				9C8898BB1C738B9800D6B02E /* ASTextKitFontSizeAdjuster.mm in Sources */,
 				D785F6631A74327E00291744 /* ASScrollNode.m in Sources */,
-				E5711A2E1C840C96009619D4 /* ASIndexedNodeContext.m in Sources */,
+				E5711A2E1C840C96009619D4 /* ASIndexedNodeContext.mm in Sources */,
 				058D0A2C195D050800B7D73C /* ASSentinel.m in Sources */,
 				9C8221971BA237B80037F19A /* ASStackBaselinePositionedLayout.mm in Sources */,
 				251B8EF81BBB3D690087C538 /* ASCollectionDataController.mm in Sources */,
@@ -2242,7 +2242,7 @@
 				69E100701CA89CB600D88C1B /* ASEnvironmentInternal.mm in Sources */,
 				254C6B891BF94F8A003EC431 /* ASTextKitRenderer+Positioning.mm in Sources */,
 				68355B341CB579B9001D4E68 /* ASImageNode+AnimatedImage.mm in Sources */,
-				E5711A301C840C96009619D4 /* ASIndexedNodeContext.m in Sources */,
+				E5711A301C840C96009619D4 /* ASIndexedNodeContext.mm in Sources */,
 				B35062511B010EFD0018CF92 /* ASDisplayNode+UIViewBridge.mm in Sources */,
 				B35061FC1B010EFD0018CF92 /* ASDisplayNode.mm in Sources */,
 				B35061FF1B010EFD0018CF92 /* ASDisplayNodeExtras.mm in Sources */,

AsyncDisplayKit/ASCollectionNode.mm

@@ -11,6 +11,7 @@
 #import "ASCollectionViewLayoutFacilitatorProtocol.h"
 #import "ASDisplayNode+Subclasses.h"
 #import "ASEnvironmentInternal.h"
+#import "ASInternalHelpers.h"
 #import "ASRangeControllerUpdateRangeProtocol+Beta.h"
 #include <vector>
 

AsyncDisplayKit/ASDisplayNode.mm

@@ -1252,7 +1252,7 @@ static bool disableNotificationsForMovingBetweenParents(ASDisplayNode *from, ASD
   // This call will apply our .hierarchyState to the new subnode.
   // If we are a managed hierarchy, as in ASCellNode trees, it will also apply our .interfaceState.
   [subnode __setSupernode:self];
-
+  
   if (self.nodeLoaded) {
     // If this node has a view or layer, force the subnode to also create its view or layer and add it to the hierarchy here.
     // Otherwise there is no way for the subnode's view or layer to enter the hierarchy, except recursing down all
@@ -1298,7 +1298,7 @@ static bool disableNotificationsForMovingBetweenParents(ASDisplayNode *from, ASD
     _subnodes = [[NSMutableArray alloc] init];
   [_subnodes insertObject:subnode atIndex:subnodeIndex];
   [subnode __setSupernode:self];
-
+  
   // Don't bother inserting the view/layer if in a rasterized subtree, because there are no layers in the hierarchy and none of this could possibly work.
   if (!_flags.shouldRasterizeDescendants && [self __shouldLoadViewOrLayer]) {
     if (_layer) {
@@ -1740,6 +1740,9 @@ static NSInteger incrementIfFound(NSInteger i) {
       
       [self exitHierarchyState:stateToEnterOrExit];
     }
+    
+    // now that we have a supernode, propagate its traits to self.
+    ASEnvironmentStatePropagateDown(self, [newSupernode environmentTraitCollection]);
   }
 }
 
@@ -1902,6 +1905,7 @@ void recursivelyTriggerDisplayForLayer(CALayer *layer, BOOL shouldBlock)
   if ((_methodOverrides & ASDisplayNodeMethodOverrideLayoutSpecThatFits) || _layoutSpecBlock != NULL) {
     ASLayoutSpec *layoutSpec = [self layoutSpecThatFits:constrainedSize];
     layoutSpec.parent = self; // This causes upward propogation of any non-default layoutable values.
+    layoutSpec.traitCollection = self.asyncTraitCollection;
     layoutSpec.isMutable = NO;
     ASLayout *layout = [layoutSpec measureWithSizeRange:constrainedSize];
     // Make sure layoutableObject of the root layout is `self`, so that the flattened layout will be structurally correct.
@@ -2722,7 +2726,12 @@ static const char *ASDisplayNodeDrawingPriorityKey = "ASDrawingPriority";
 
 - (ASEnvironmentTraitCollection)environmentTraitCollection
 {
-  return _environmentState.traitCollection;
+  return _environmentState.environmentTraitCollection;
+}
+
+- (void)setEnvironmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection
+{
+  _environmentState.environmentTraitCollection = environmentTraitCollection;
 }
 
 ASEnvironmentLayoutOptionsForwarding
@@ -2731,7 +2740,7 @@ ASEnvironmentLayoutExtensibilityForwarding
 - (ASTraitCollection *)asyncTraitCollection
 {
   ASDN::MutexLocker l(_propertyLock);
-  return [ASTraitCollection traitCollectionWithASEnvironmentTraitCollection:_environmentState.traitCollection];
+  return [ASTraitCollection traitCollectionWithASEnvironmentTraitCollection:self.environmentTraitCollection];
 }
 
 #if TARGET_OS_TV

AsyncDisplayKit/ASTableNode.mm

@@ -7,10 +7,11 @@
 //
 
 #import "ASEnvironmentInternal.h"
-#import "ASFlowLayoutController.h"
-#import "ASTableViewInternal.h"
 #import "ASDisplayNode+Subclasses.h"
+#import "ASFlowLayoutController.h"
+#import "ASInternalHelpers.h"
 #import "ASRangeControllerUpdateRangeProtocol+Beta.h"
+#import "ASTableViewInternal.h"
 
 @interface _ASTablePendingState : NSObject
 @property (weak, nonatomic) id <ASTableDelegate>   delegate;

AsyncDisplayKit/ASViewController.h

@@ -33,7 +33,7 @@ typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitWindowSizeBlock)(C
  *  ASVC keeps a strong reference to the context to make sure that it stays alive. If you change this value
  *  it will propagate the change to the subnodes.
  */
-@property (nonatomic, strong) id _Nullable traitColectionContext;
+@property (nonatomic, strong) id _Nullable traitCollectionContext;
 
 /**
  * Set this block to customize the ASDisplayTraits returned when the VC transitions to the given traitCollection.

AsyncDisplayKit/ASViewController.mm

@@ -8,6 +8,7 @@
 
 #import "ASViewController.h"
 #import "ASAssert.h"
+#import "ASAvailability.h"
 #import "ASDimension.h"
 #import "ASDisplayNodeInternal.h"
 #import "ASDisplayNode+FrameworkPrivate.h"
@@ -55,12 +56,12 @@
 
 - (void)dealloc
 {
-  if (_traitColectionContext != nil) {
+  if (_traitCollectionContext != nil) {
     // The setter will iterate through the VC's subnodes and replace the traitCollectionContext in their ASEnvironmentTraitCollection with nil.
     // Since the VC holds the only strong reference to this context and we are in the process of destroying
     // the VC, all the references in the subnodes will be unsafe unless we nil them out. More than likely all the subnodes will be dealloc'ed
     // as part of the VC being dealloc'ed, but this is just to make extra sure.
-    self.traitColectionContext = nil;
+    self.traitCollectionContext = nil;
   }
 }
 
@@ -82,6 +83,13 @@
   _node.frame = frame;
   _node.autoresizingMask = autoresizingMask;
   self.view = view;
+  
+  // ensure that self.node has a valid trait collection before a subclass's implementation of viewDidLoad.
+  // Any subnodes added in viewDidLoad will then inherit the proper environment.
+  if (AS_AT_LEAST_IOS8) {
+    ASEnvironmentTraitCollection traitCollection = [self environmentTraitCollectionForUITraitCollection:self.traitCollection];
+    [self progagateNewEnvironmentTraitCollection:traitCollection];
+  }
 }
 
 - (void)viewWillLayoutSubviews
@@ -187,52 +195,53 @@ ASVisibilityDepthImplementation;
 
 #pragma mark - ASEnvironmentTraitCollection
 
-- (void)setTraitColectionContext:(id)traitColectionContext
+- (void)setTraitCollectionContext:(id)traitCollectionContext
 {
-  if (_traitColectionContext != traitColectionContext) {
+  if (_traitCollectionContext != traitCollectionContext) {
-    // propagate first so that nodes aren't hanging around with a dealloc'ed pointer
+    // nil out the displayContext in the subnodes so they aren't hanging around with a dealloc'ed pointer don't set
-    ASEnvironmentTraitCollectionUpdateDisplayContext(self.node, traitColectionContext);
+    // the new context yet as this will cause ASEnvironmentTraitCollectionIsEqualToASEnvironmentTraitCollection to fail
+    ASEnvironmentTraitCollectionUpdateDisplayContext(self.node, nil);
     
-    _traitColectionContext = traitColectionContext;
+    _traitCollectionContext = traitCollectionContext;
   }
 }
 
-- (ASEnvironmentTraitCollection)displayTraitsForTraitCollection:(UITraitCollection *)traitCollection
+- (ASEnvironmentTraitCollection)environmentTraitCollectionForUITraitCollection:(UITraitCollection *)traitCollection
 {
   if (self.overrideDisplayTraitsWithTraitCollection) {
     ASTraitCollection *asyncTraitCollection = self.overrideDisplayTraitsWithTraitCollection(traitCollection);
-    self.traitColectionContext = asyncTraitCollection.traitCollectionContext;
+    self.traitCollectionContext = asyncTraitCollection.traitCollectionContext;
     return [asyncTraitCollection environmentTraitCollection];
   }
   
   ASEnvironmentTraitCollection asyncTraitCollection = ASEnvironmentTraitCollectionFromUITraitCollection(traitCollection);
-  asyncTraitCollection.displayContext = self.traitColectionContext;
+  asyncTraitCollection.displayContext = self.traitCollectionContext;
   return asyncTraitCollection;
 }
 
-- (ASEnvironmentTraitCollection)displayTraitsForWindowSize:(CGSize)windowSize
+- (ASEnvironmentTraitCollection)environmentTraitCollectionForWindowSize:(CGSize)windowSize
 {
   if (self.overrideDisplayTraitsWithWindowSize) {
     ASTraitCollection *traitCollection = self.overrideDisplayTraitsWithWindowSize(windowSize);
-    self.traitColectionContext = traitCollection.traitCollectionContext;
+    self.traitCollectionContext = traitCollection.traitCollectionContext;
     return [traitCollection environmentTraitCollection];
   }
   return self.node.environmentTraitCollection;
 }
 
-- (void)progagateNewDisplayTraits:(ASEnvironmentTraitCollection)traitCollection
+- (void)progagateNewEnvironmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection
 {
   ASEnvironmentState environmentState = self.node.environmentState;
-  ASEnvironmentTraitCollection oldTraitCollection = environmentState.traitCollection;
+  ASEnvironmentTraitCollection oldEnvironmentTraitCollection = environmentState.environmentTraitCollection;
   
-  if (ASEnvironmentTraitCollectionIsEqualToASEnvironmentTraitCollection(traitCollection, oldTraitCollection) == NO) {
+  if (ASEnvironmentTraitCollectionIsEqualToASEnvironmentTraitCollection(environmentTraitCollection, oldEnvironmentTraitCollection) == NO) {
-    environmentState.traitCollection = traitCollection;
+    environmentState.environmentTraitCollection = environmentTraitCollection;
     self.node.environmentState = environmentState;
     [self.node setNeedsLayout];
     
     NSArray<id<ASEnvironment>> *children = [self.node children];
     for (id<ASEnvironment> child in children) {
-      ASEnvironmentStatePropagateDown(child, environmentState.traitCollection);
+      ASEnvironmentStatePropagateDown(child, environmentState.environmentTraitCollection);
     }
   }
 }
@@ -241,24 +250,24 @@ ASVisibilityDepthImplementation;
 {
   [super traitCollectionDidChange:previousTraitCollection];
   
-  ASEnvironmentTraitCollection traitCollection = [self displayTraitsForTraitCollection:self.traitCollection];
+  ASEnvironmentTraitCollection environmentTraitCollection = [self environmentTraitCollectionForUITraitCollection:self.traitCollection];
-  [self progagateNewDisplayTraits:traitCollection];
+  [self progagateNewEnvironmentTraitCollection:environmentTraitCollection];
 }
 
 - (void)willTransitionToTraitCollection:(UITraitCollection *)newCollection withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
 {
   [super willTransitionToTraitCollection:newCollection withTransitionCoordinator:coordinator];
   
-  ASEnvironmentTraitCollection traitCollection = [self displayTraitsForTraitCollection:newCollection];
+  ASEnvironmentTraitCollection environmentTraitCollection = [self environmentTraitCollectionForUITraitCollection:newCollection];
-  [self progagateNewDisplayTraits:traitCollection];
+  [self progagateNewEnvironmentTraitCollection:environmentTraitCollection];
 }
 
 - (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
 {
   [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
   
-  ASEnvironmentTraitCollection traitCollection = [self displayTraitsForWindowSize:size];
+  ASEnvironmentTraitCollection environmentTraitCollection = [self environmentTraitCollectionForWindowSize:size];
-  [self progagateNewDisplayTraits:traitCollection];
+  [self progagateNewEnvironmentTraitCollection:environmentTraitCollection];
 }
 
 @end

AsyncDisplayKit/Details/ASCollectionDataController.mm

@@ -158,6 +158,9 @@
 
 - (void)_populateSupplementaryNodesOfKind:(NSString *)kind withMutableContexts:(NSMutableArray<ASIndexedNodeContext *> *)contexts
 {
+  id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
+  ASEnvironmentTraitCollection environmentTraitCollection = environment.environmentTraitCollection;
+  
   NSUInteger sectionCount = [self.collectionDataSource dataController:self numberOfSectionsForSupplementaryNodeOfKind:kind];
   for (NSUInteger i = 0; i < sectionCount; i++) {
     NSIndexPath *sectionIndexPath = [[NSIndexPath alloc] initWithIndex:i];
@@ -176,7 +179,8 @@
       ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:kind atIndexPath:indexPath];
       ASIndexedNodeContext *context = [[ASIndexedNodeContext alloc] initWithNodeBlock:supplementaryCellBlock
                                                                             indexPath:indexPath
-                                                                      constrainedSize:constrainedSize];
+                                                                      constrainedSize:constrainedSize
+                                                           environmentTraitCollection:environmentTraitCollection];
       [contexts addObject:context];
     }
   }
@@ -184,6 +188,9 @@
 
 - (void)_populateSupplementaryNodesOfKind:(NSString *)kind withSections:(NSIndexSet *)sections mutableContexts:(NSMutableArray<ASIndexedNodeContext *> *)contexts
 {
+  id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
+  ASEnvironmentTraitCollection environmentTraitCollection = environment.environmentTraitCollection;
+  
   [sections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {
     NSUInteger rowNum = [self.collectionDataSource dataController:self supplementaryNodesOfKind:kind inSection:idx];
     NSIndexPath *sectionIndex = [[NSIndexPath alloc] initWithIndex:idx];
@@ -201,7 +208,8 @@
       ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:kind atIndexPath:indexPath];
       ASIndexedNodeContext *context = [[ASIndexedNodeContext alloc] initWithNodeBlock:supplementaryCellBlock
                                                                             indexPath:indexPath
-                                                                        constrainedSize:constrainedSize];
+                                                                        constrainedSize:constrainedSize
+                                                           environmentTraitCollection:environmentTraitCollection];
       [contexts addObject:context];
     }
   }];

AsyncDisplayKit/Details/ASDataController.mm

@@ -519,6 +519,9 @@ static void *kASSizingQueueContext = &kASSizingQueueContext;
  */
 - (NSArray<ASIndexedNodeContext *> *)_populateFromDataSourceWithSectionIndexSet:(NSIndexSet *)indexSet
 {
+  id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
+  ASEnvironmentTraitCollection environmentTraitCollection = environment.environmentTraitCollection;
+  
   NSMutableArray<ASIndexedNodeContext *> *contexts = [NSMutableArray array];
   [indexSet enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {
     NSUInteger rowNum = [_dataSource dataController:self rowsInSection:idx];
@@ -527,18 +530,11 @@ static void *kASSizingQueueContext = &kASSizingQueueContext;
       NSIndexPath *indexPath = [sectionIndex indexPathByAddingIndex:i];
       ASCellNodeBlock nodeBlock = [_dataSource dataController:self nodeBlockAtIndexPath:indexPath];
       
-      // When creating a node, make sure to pass along the current display traits so it will be laid out properly
-      ASCellNodeBlock nodeBlockPropagatingDisplayTraits = ^{
-        ASCellNode *cellNode = nodeBlock();
-        id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
-        ASEnvironmentStatePropagateDown(cellNode, [environment environmentTraitCollection]);
-        return cellNode;
-      };
-      
       ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:ASDataControllerRowNodeKind atIndexPath:indexPath];
-      [contexts addObject:[[ASIndexedNodeContext alloc] initWithNodeBlock:nodeBlockPropagatingDisplayTraits
+      [contexts addObject:[[ASIndexedNodeContext alloc] initWithNodeBlock:nodeBlock
                                                                 indexPath:indexPath
-                                                          constrainedSize:constrainedSize]];
+                                                          constrainedSize:constrainedSize
+                                               environmentTraitCollection:environmentTraitCollection]];
     }
   }];
   return contexts;
@@ -791,12 +787,16 @@ static void *kASSizingQueueContext = &kASSizingQueueContext;
     NSMutableArray<ASIndexedNodeContext *> *contexts = [[NSMutableArray alloc] initWithCapacity:indexPaths.count];
 
     [self accessDataSourceWithBlock:^{
+      id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
+      ASEnvironmentTraitCollection environmentTraitCollection = environment.environmentTraitCollection;
+      
       for (NSIndexPath *indexPath in sortedIndexPaths) {
         ASCellNodeBlock nodeBlock = [_dataSource dataController:self nodeBlockAtIndexPath:indexPath];
         ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:ASDataControllerRowNodeKind atIndexPath:indexPath];
         [contexts addObject:[[ASIndexedNodeContext alloc] initWithNodeBlock:nodeBlock
                                                                   indexPath:indexPath
-                                                            constrainedSize:constrainedSize]];
+                                                            constrainedSize:constrainedSize
+                                                 environmentTraitCollection:environmentTraitCollection]];
       }
 
       [_editingTransactionQueue addOperationWithBlock:^{
@@ -842,12 +842,16 @@ static void *kASSizingQueueContext = &kASSizingQueueContext;
       // FIXME: Shouldn't deletes be sorted in descending order?
       [indexPaths sortedArrayUsingSelector:@selector(compare:)];
       
+      id<ASEnvironment> environment = [self.environmentDelegate dataControllerEnvironment];
+      ASEnvironmentTraitCollection environmentTraitCollection = environment.environmentTraitCollection;
+      
       for (NSIndexPath *indexPath in indexPaths) {
         ASCellNodeBlock nodeBlock = [_dataSource dataController:self nodeBlockAtIndexPath:indexPath];
         ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:ASDataControllerRowNodeKind atIndexPath:indexPath];
         [contexts addObject:[[ASIndexedNodeContext alloc] initWithNodeBlock:nodeBlock
                                                                   indexPath:indexPath
-                                                            constrainedSize:constrainedSize]];
+                                                            constrainedSize:constrainedSize
+                                                 environmentTraitCollection:environmentTraitCollection]];
       }
 
       [_editingTransactionQueue addOperationWithBlock:^{

AsyncDisplayKit/Details/ASEnvironment.h

@@ -97,7 +97,7 @@ extern BOOL ASEnvironmentTraitCollectionIsEqualToASEnvironmentTraitCollection(AS
 typedef struct ASEnvironmentState {
   struct ASEnvironmentHierarchyState hierarchyState;
   struct ASEnvironmentLayoutOptionsState layoutOptionsState;
-  struct ASEnvironmentTraitCollection traitCollection;
+  struct ASEnvironmentTraitCollection environmentTraitCollection;
 } ASEnvironmentState;
 extern ASEnvironmentState ASEnvironmentStateMakeDefault();
 
@@ -137,6 +137,8 @@ ASDISPLAYNODE_EXTERN_C_END
 /// convenience method. Users should access the trait collections through the NSObject based asyncTraitCollection API
 - (ASEnvironmentTraitCollection)environmentTraitCollection;
 
+/// sets a trait collection on this environment state.
+- (void)setEnvironmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection;
 @end
 
 // ASCollection/TableNodes don't actually have ASCellNodes as subnodes. Because of this we can't rely on display trait
@@ -150,17 +152,19 @@ ASDISPLAYNODE_EXTERN_C_END
 - (void)setEnvironmentState:(ASEnvironmentState)environmentState\
 {\
   ASDN::MutexLocker l(lock);\
-  ASEnvironmentTraitCollection oldTraits = self.environmentState.traitCollection;\
+  ASEnvironmentTraitCollection oldTraits = self.environmentState.environmentTraitCollection;\
   [super setEnvironmentState:environmentState];\
-  ASEnvironmentTraitCollection currentTraits = environmentState.traitCollection;\
+  ASEnvironmentTraitCollection currentTraits = environmentState.environmentTraitCollection;\
   if (ASEnvironmentTraitCollectionIsEqualToASEnvironmentTraitCollection(currentTraits, oldTraits) == NO) {\
-    NSArray<NSArray <ASCellNode *> *> *completedNodes = [self.view.dataController completedNodes];\
+    ASPerformBlockOnMainThread(^{\
-    for (NSArray *sectionArray in completedNodes) {\
+      NSArray<NSArray <ASCellNode *> *> *completedNodes = [self.view.dataController completedNodes];\
-      for (ASCellNode *cellNode in sectionArray) {\
+      for (NSArray *sectionArray in completedNodes) {\
-        ASEnvironmentStatePropagateDown(cellNode, currentTraits);\
+        for (ASCellNode *cellNode in sectionArray) {\
-        [cellNode setNeedsLayout];\
+          ASEnvironmentStatePropagateDown(cellNode, currentTraits);\
+          [cellNode setNeedsLayout];\
+        }\
       }\
-    }\
+    });\
   }\
 }\
 

AsyncDisplayKit/Details/ASEnvironment.mm

@@ -29,13 +29,13 @@ ASEnvironmentHierarchyState _ASEnvironmentHierarchyStateMakeDefault()
 extern void ASEnvironmentTraitCollectionUpdateDisplayContext(id<ASEnvironment> rootEnvironment, id context)
 {
   ASEnvironmentState envState = [rootEnvironment environmentState];
-  ASEnvironmentTraitCollection displayTraits = envState.traitCollection;
+  ASEnvironmentTraitCollection environmentTraitCollection = envState.environmentTraitCollection;
-  displayTraits.displayContext = context;
+  environmentTraitCollection.displayContext = context;
-  envState.traitCollection = displayTraits;
+  envState.environmentTraitCollection = environmentTraitCollection;
   [rootEnvironment setEnvironmentState:envState];
   
   for (id<ASEnvironment> child in [rootEnvironment children]) {
-    ASEnvironmentStatePropagateDown(child, displayTraits);
+    ASEnvironmentStatePropagateDown(child, environmentTraitCollection);
   }
 }
 
@@ -77,7 +77,7 @@ ASEnvironmentState ASEnvironmentStateMakeDefault()
   return (ASEnvironmentState) {
     .layoutOptionsState = _ASEnvironmentLayoutOptionsStateMakeDefault(),
     .hierarchyState = _ASEnvironmentHierarchyStateMakeDefault(),
-    .traitCollection = _ASEnvironmentTraitCollectionMakeDefault()
+    .environmentTraitCollection = _ASEnvironmentTraitCollectionMakeDefault()
   };
 }
 

AsyncDisplayKit/Details/ASIndexedNodeContext.h

@@ -7,15 +7,18 @@
 //
 
 #import <AsyncDisplayKit/ASDataController.h>
+#import <AsyncDisplayKit/ASEnvironment.h>
 
 @interface ASIndexedNodeContext : NSObject
 
 @property (nonatomic, readonly, strong) NSIndexPath *indexPath;
 @property (nonatomic, readonly, assign) ASSizeRange constrainedSize;
+@property (nonatomic, readonly, assign) ASEnvironmentTraitCollection environmentTraitCollection;
 
 - (instancetype)initWithNodeBlock:(ASCellNodeBlock)nodeBlock
                         indexPath:(NSIndexPath *)indexPath
-                  constrainedSize:(ASSizeRange)constrainedSize;
+                  constrainedSize:(ASSizeRange)constrainedSize
+       environmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection;
 
 /**
  * Returns a node allocated by executing node block. Node block will be nil out immediately.

AsyncDisplayKit/Details/ASIndexedNodeContext.mm

@@ -7,6 +7,8 @@
 //
 
 #import "ASIndexedNodeContext.h"
+#import "ASEnvironmentInternal.h"
+#import "ASCellNode.h"
 
 @interface ASIndexedNodeContext ()
 
@@ -19,7 +21,8 @@
 
 - (instancetype)initWithNodeBlock:(ASCellNodeBlock)nodeBlock
                         indexPath:(NSIndexPath *)indexPath
-                  constrainedSize:(ASSizeRange)constrainedSize;
+                  constrainedSize:(ASSizeRange)constrainedSize
+       environmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection
 {
   NSAssert(nodeBlock != nil && indexPath != nil, @"Node block and index path must not be nil");
   self = [super init];
@@ -27,6 +30,7 @@
     _nodeBlock = nodeBlock;
     _indexPath = indexPath;
     _constrainedSize = constrainedSize;
+    _environmentTraitCollection = environmentTraitCollection;
   }
   return self;
 }
@@ -36,6 +40,7 @@
   NSAssert(_nodeBlock != nil, @"Node block is gone. Should not execute it more than once");
   ASCellNode *node = _nodeBlock();
   _nodeBlock = nil;
+  ASEnvironmentStatePropagateDown(node, _environmentTraitCollection);
   return node;
 }
 

AsyncDisplayKit/Details/ASTraitCollection.h

@@ -28,7 +28,7 @@
  *  Be aware that internally this context is held by a C struct which cannot retain the pointer. 
  *  ASTraitCollection is generally a very short-lived class, existing only to provide a non-struct API
  *  to trait collections. When an ASTraitCollection is returned via one of ASViewController's 2 
- *  custom trait collection creation blocks, traitColectionContext is assigned to the VC's traitColectionContext.
+ *  custom trait collection creation blocks, traitCollectionContext is assigned to the VC's traitCollectionContext.
  *  This makes sure that the VC is the owner of the context and ASEnvironmentTraitCollections will not
  *  have a reference to a dangling pointer.
  */
@@ -50,5 +50,6 @@
 
 
 - (ASEnvironmentTraitCollection)environmentTraitCollection;
+- (BOOL)isEqualToTraitCollection:(ASTraitCollection *)traitCollection;
 
 @end

AsyncDisplayKit/Details/ASTraitCollection.m

@@ -95,4 +95,14 @@
   };
 }
 
+- (BOOL)isEqualToTraitCollection:(ASTraitCollection *)traitCollection
+{
+  return self.displayScale == traitCollection.displayScale &&
+  self.horizontalSizeClass == traitCollection.horizontalSizeClass &&
+  self.verticalSizeClass == traitCollection.verticalSizeClass &&
+  self.userInterfaceIdiom == traitCollection.userInterfaceIdiom &&
+  self.traitCollectionContext == traitCollection.traitCollectionContext &&
+  self.forceTouchCapability == traitCollection.forceTouchCapability;
+}
+
 @end

AsyncDisplayKit/Layout/ASBackgroundLayoutSpec.mm

@@ -68,15 +68,4 @@ static NSString * const kBackgroundChildKey = @"kBackgroundChildKey";
   return [super childForIdentifier:kBackgroundChildKey];
 }
 
-- (void)setChildren:(NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-}
-
-- (NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-  return nil;
-}
-
 @end

AsyncDisplayKit/Layout/ASInsetLayoutSpec.mm

@@ -115,15 +115,4 @@ static CGFloat centerInset(CGFloat outer, CGFloat inner)
   return [ASLayout layoutWithLayoutableObject:self size:computedSize sublayouts:@[sublayout]];
 }
 
-- (void)setChildren:(NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-}
-
-- (NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-  return nil;
-}
-
 @end

AsyncDisplayKit/Layout/ASLayoutSpec.h

@@ -11,6 +11,8 @@
 #import <AsyncDisplayKit/ASLayoutable.h>
 #import <AsyncDisplayKit/ASAsciiArtBoxCreator.h>
 
+@class ASTraitCollection;
+
 NS_ASSUME_NONNULL_BEGIN
 
 /** A layout spec is an immutable object that describes a layout, loosely inspired by React. */
@@ -23,6 +25,8 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, assign) BOOL isMutable;
 
+@property (nonatomic, strong, nullable) ASTraitCollection *traitCollection;
+
 - (instancetype)init;
 
 /**

AsyncDisplayKit/Layout/ASLayoutSpec.mm

@@ -26,7 +26,6 @@
   ASEnvironmentState _environmentState;
   ASDN::RecursiveMutex _propertyLock;
   
-  id<ASLayoutable> _child;
   NSArray *_children;
   NSMutableDictionary *_childrenWithIdentifier;
 }
@@ -45,7 +44,7 @@
   }
   _isMutable = YES;
   _environmentState = ASEnvironmentStateMakeDefault();
-  
+  _children = [NSArray array];
   return self;
 }
 
@@ -113,28 +112,46 @@
   }
 }
 
-- (void)setChild:(id<ASLayoutable>)child;
+- (void)setChild:(id<ASLayoutable>)child
 {
   ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
-  
+  if (child) {
-  id<ASLayoutable> finalLayoutable = [self layoutableToAddFromLayoutable:child];
+    id<ASLayoutable> finalLayoutable = [self layoutableToAddFromLayoutable:child];
-  _child = finalLayoutable;
+    if (finalLayoutable) {
-  [self propagateUpLayoutable:finalLayoutable];
+      _children = @[finalLayoutable];
+      [self propagateUpLayoutable:finalLayoutable];
+    }
+  } else {
+    // remove the only child
+    _children = [NSArray array];
+  }
 }
 
 - (void)setChild:(id<ASLayoutable>)child forIdentifier:(NSString *)identifier
 {
   ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
-  
+  if (child) {
-  id<ASLayoutable> finalLayoutable = [self layoutableToAddFromLayoutable:child];
+    id<ASLayoutable> finalLayoutable = [self layoutableToAddFromLayoutable:child];
-  self.childrenWithIdentifier[identifier] = finalLayoutable;
+    self.childrenWithIdentifier[identifier] = finalLayoutable;
+    if (finalLayoutable) {
+      _children = [_children arrayByAddingObject:finalLayoutable];
+    }
+  } else {
+    id<ASLayoutable> oldChild = self.childrenWithIdentifier[identifier];
+    if (oldChild) {
+      self.childrenWithIdentifier[identifier] = nil;
+      NSMutableArray *mutableChildren = [_children mutableCopy];
+      [mutableChildren removeObject:oldChild];
+      _children = [mutableChildren copy];
+    }
+  }
   
   // TODO: Should we propagate up the layoutable at it could happen that multiple children will propagated up their
   //       layout options and one child will overwrite values from another child
   // [self propagateUpLayoutable:finalLayoutable];
 }
 
-- (void)setChildren:(NSArray *)children
+- (void)setChildren:(NSArray<id<ASLayoutable>> *)children
 {
   ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
   
@@ -146,6 +163,8 @@
   _children = nil;
   if (finalChildren.size() > 0) {
     _children = [NSArray arrayWithObjects:&finalChildren[0] count:finalChildren.size()];
+  } else {
+    _children = [NSArray array];
   }
 }
 
@@ -156,14 +175,21 @@
 
 - (id<ASLayoutable>)child
 {
-  return _child;
+  return [_children firstObject];
 }
 
 - (NSArray *)children
 {
-  return [_children copy];
+  return _children;
 }
 
+- (void)setTraitCollection:(ASTraitCollection *)traitCollection
+{
+  if ([traitCollection isEqualToTraitCollection:self.traitCollection] == NO) {
+    _traitCollection = traitCollection;
+    ASEnvironmentStatePropagateDown(self, [traitCollection environmentTraitCollection]);
+  }
+}
 
 #pragma mark - ASEnvironment
 
@@ -201,7 +227,12 @@
 
 - (ASEnvironmentTraitCollection)environmentTraitCollection
 {
-  return _environmentState.traitCollection;
+  return _environmentState.environmentTraitCollection;
+}
+
+- (void)setEnvironmentTraitCollection:(ASEnvironmentTraitCollection)environmentTraitCollection
+{
+  _environmentState.environmentTraitCollection = environmentTraitCollection;
 }
 
 ASEnvironmentLayoutOptionsForwarding
@@ -210,7 +241,7 @@ ASEnvironmentLayoutExtensibilityForwarding
 - (ASTraitCollection *)asyncTraitCollection
 {
   ASDN::MutexLocker l(_propertyLock);
-  return [ASTraitCollection traitCollectionWithASEnvironmentTraitCollection:_environmentState.traitCollection];
+  return [ASTraitCollection traitCollectionWithASEnvironmentTraitCollection:self.environmentTraitCollection];
 }
 
 @end

AsyncDisplayKit/Layout/ASOverlayLayoutSpec.mm

@@ -61,17 +61,6 @@ static NSString * const kOverlayChildKey = @"kOverlayChildKey";
   return [ASLayout layoutWithLayoutableObject:self size:contentsLayout.size sublayouts:sublayouts];
 }
 
-- (void)setChildren:(NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-}
-
-- (NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-  return nil;
-}
-
 @end
 
 @implementation ASOverlayLayoutSpec (Debugging)

AsyncDisplayKit/Layout/ASRatioLayoutSpec.mm

@@ -75,17 +75,6 @@
   return [ASLayout layoutWithLayoutableObject:self size:sublayout.size sublayouts:@[sublayout]];
 }
 
-- (void)setChildren:(NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-}
-
-- (NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-  return nil;
-}
-
 @end
 
 @implementation ASRatioLayoutSpec (Debugging)

AsyncDisplayKit/Layout/ASRelativeLayoutSpec.mm

@@ -92,17 +92,6 @@
   return [ASLayout layoutWithLayoutableObject:self size:size sublayouts:@[sublayout]];
 }
 
-- (void)setChildren:(NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-}
-
-- (NSArray *)children
-{
-  ASDisplayNodeAssert(NO, @"not supported by this layout spec");
-  return nil;
-}
-
 - (CGFloat)proportionOfAxisForAxisPosition:(ASRelativeLayoutSpecPosition)position
 {
   if ((position & ASRelativeLayoutSpecPositionCenter) != 0) {

AsyncDisplayKit/Layout/ASStackLayoutSpec.mm

@@ -121,17 +121,6 @@
   _baselineRelativeArrangement = baselineRelativeArrangement;
 }
 
-- (void)setChild:(id<ASLayoutable>)child forIdentifier:(NSString *)identifier
-{
-  ASDisplayNodeAssert(NO, @"ASStackLayoutSpec only supports setChildren");
-}
-
-- (id<ASLayoutable>)childForIdentifier:(NSString *)identifier
-{
-  ASDisplayNodeAssert(NO, @"ASStackLayoutSpec only supports children");
-  return nil;
-}
-
 - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
 {
   if (self.children.count == 0) {

AsyncDisplayKit/Layout/ASStaticLayoutSpec.mm

@@ -72,17 +72,6 @@
                                    sublayouts:sublayouts];
 }
 
-- (void)setChild:(id<ASLayoutable>)child forIdentifier:(NSString *)identifier
-{
-  ASDisplayNodeAssert(NO, @"ASStaticLayoutSpec only supports setChildren");
-}
-
-- (id<ASLayoutable>)childForIdentifier:(NSString *)identifier
-{
-  ASDisplayNodeAssert(NO, @"ASStaticLayoutSpec only supports children");
-  return nil;
-}
-
 @end
 
 @implementation ASStaticLayoutSpec (ASEnvironment)

AsyncDisplayKit/Private/ASEnvironmentInternal.h

@@ -58,14 +58,14 @@ ASEnvironmentState ASEnvironmentMergeObjectAndState(ASEnvironmentState environme
 template <typename ASEnvironmentStateType>
 void ASEnvironmentStatePropagateDown(id<ASEnvironment> object, ASEnvironmentStateType state) {
   ASEnvironmentPerformBlockOnObjectAndChildren(object, ^(id<ASEnvironment> node) {
-    object.environmentState = ASEnvironmentMergeObjectAndState(object.environmentState, state, ASEnvironmentStatePropagation::DOWN);
+    node.environmentState = ASEnvironmentMergeObjectAndState(node.environmentState, state, ASEnvironmentStatePropagation::DOWN);
   });
 }
 
 template <typename ASEnvironmentStateType>
 void ASEnvironmentStatePropagateUp(id<ASEnvironment> object, ASEnvironmentStateType state) {
   ASEnvironmentPerformBlockOnObjectAndParents(object, ^(id<ASEnvironment> node) {
-    object.environmentState = ASEnvironmentMergeObjectAndState(object.environmentState, state, ASEnvironmentStatePropagation::UP);
+    node.environmentState = ASEnvironmentMergeObjectAndState(node.environmentState, state, ASEnvironmentStatePropagation::UP);
   });
 }
 

AsyncDisplayKit/Private/ASEnvironmentInternal.mm

@@ -201,14 +201,14 @@ ASEnvironmentState ASEnvironmentMergeObjectAndState(ASEnvironmentState childEnvi
   
   // Support propagate down
   if (propagation == ASEnvironmentStatePropagation::DOWN) {
-    ASEnvironmentTraitCollection childTraitCollection = childEnvironmentState.traitCollection;
+    ASEnvironmentTraitCollection childTraitCollection = childEnvironmentState.environmentTraitCollection;
     childTraitCollection.horizontalSizeClass = parentTraitCollection.horizontalSizeClass;
     childTraitCollection.verticalSizeClass = parentTraitCollection.verticalSizeClass;
     childTraitCollection.userInterfaceIdiom = parentTraitCollection.userInterfaceIdiom;
     childTraitCollection.forceTouchCapability = parentTraitCollection.forceTouchCapability;
     childTraitCollection.displayScale = parentTraitCollection.displayScale;
     childTraitCollection.displayContext = parentTraitCollection.displayContext;
-    childEnvironmentState.traitCollection = childTraitCollection;
+    childEnvironmentState.environmentTraitCollection = childTraitCollection;
 
   }
   return childEnvironmentState;

examples_extra/ASTraitCollection/Podfile

@@ -1,3 +1,5 @@
 source 'https://github.com/CocoaPods/Specs.git'
-platform :ios, '8.0'
+platform :ios, '7.0'
-pod 'AsyncDisplayKit', :path => '../..'
+target 'Sample' do
+	pod 'AsyncDisplayKit', :path => '../..'
+end

examples_extra/ASTraitCollection/Sample.xcodeproj/project.pbxproj

@@ -10,7 +10,7 @@
 		05E2128719D4DB510098F589 /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = 05E2128619D4DB510098F589 /* main.m */; };
 		05E2128A19D4DB510098F589 /* AppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = 05E2128919D4DB510098F589 /* AppDelegate.m */; };
 		05E2128D19D4DB510098F589 /* ViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 05E2128C19D4DB510098F589 /* ViewController.m */; };
-		3EC0CDCBA10D483D9F386E5E /* libPods.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 3D24B17D1E4A4E7A9566C5E9 /* libPods.a */; };
+		1BEECAB53F4B61DCB949ED44 /* libPods-Sample.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 1EEDFC574739077BA65E0CF5 /* libPods-Sample.a */; };
 		9C37D01E1CC94BC9004C8BC1 /* Launch Screen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 9C37D01D1CC94BC9004C8BC1 /* Launch Screen.storyboard */; };
 		9CACC7811CCEAF9E009A1613 /* TableViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 9CACC7801CCEAF9E009A1613 /* TableViewController.m */; };
 		9CACC7841CCEAFAE009A1613 /* CollectionViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 9CACC7831CCEAFAE009A1613 /* CollectionViewController.m */; };
@@ -19,6 +19,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		056298286C03B7760575CC56 /* Pods-Sample.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Sample.debug.xcconfig"; path = "Pods/Target Support Files/Pods-Sample/Pods-Sample.debug.xcconfig"; sourceTree = "<group>"; };
 		05E2128119D4DB510098F589 /* Sample.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Sample.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		05E2128519D4DB510098F589 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		05E2128619D4DB510098F589 /* main.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = main.m; sourceTree = "<group>"; };
@@ -27,6 +28,7 @@
 		05E2128B19D4DB510098F589 /* ViewController.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ViewController.h; sourceTree = "<group>"; };
 		05E2128C19D4DB510098F589 /* ViewController.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = ViewController.m; sourceTree = "<group>"; };
 		088AA6578212BE9BFBB07B70 /* Pods.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = Pods.release.xcconfig; path = "Pods/Target Support Files/Pods/Pods.release.xcconfig"; sourceTree = "<group>"; };
+		1EEDFC574739077BA65E0CF5 /* libPods-Sample.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-Sample.a"; sourceTree = BUILT_PRODUCTS_DIR; };
 		3D24B17D1E4A4E7A9566C5E9 /* libPods.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = libPods.a; sourceTree = BUILT_PRODUCTS_DIR; };
 		9C37D01D1CC94BC9004C8BC1 /* Launch Screen.storyboard */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.storyboard; path = "Launch Screen.storyboard"; sourceTree = "<group>"; };
 		9CACC77F1CCEAF9E009A1613 /* TableViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TableViewController.h; sourceTree = "<group>"; };
@@ -37,6 +39,7 @@
 		9CACC7861CCEBD3B009A1613 /* KittenNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = KittenNode.m; sourceTree = "<group>"; };
 		9CACC7881CCEC82C009A1613 /* OverrideViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OverrideViewController.h; sourceTree = "<group>"; };
 		9CACC7891CCEC82C009A1613 /* OverrideViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = OverrideViewController.m; sourceTree = "<group>"; };
+		A7F0013FBBCBEA0C9FB68986 /* Pods-Sample.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Sample.release.xcconfig"; path = "Pods/Target Support Files/Pods-Sample/Pods-Sample.release.xcconfig"; sourceTree = "<group>"; };
 		C068F1D3F0CC317E895FCDAB /* Pods.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = Pods.debug.xcconfig; path = "Pods/Target Support Files/Pods/Pods.debug.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -45,7 +48,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				3EC0CDCBA10D483D9F386E5E /* libPods.a in Frameworks */,
+				1BEECAB53F4B61DCB949ED44 /* libPods-Sample.a in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -107,6 +110,7 @@
 			isa = PBXGroup;
 			children = (
 				3D24B17D1E4A4E7A9566C5E9 /* libPods.a */,
+				1EEDFC574739077BA65E0CF5 /* libPods-Sample.a */,
 			);
 			name = Frameworks;
 			sourceTree = "<group>";
@@ -116,6 +120,8 @@
 			children = (
 				C068F1D3F0CC317E895FCDAB /* Pods.debug.xcconfig */,
 				088AA6578212BE9BFBB07B70 /* Pods.release.xcconfig */,
+				056298286C03B7760575CC56 /* Pods-Sample.debug.xcconfig */,
+				A7F0013FBBCBEA0C9FB68986 /* Pods-Sample.release.xcconfig */,
 			);
 			name = Pods;
 			sourceTree = "<group>";
@@ -127,12 +133,12 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 05E212A419D4DB510098F589 /* Build configuration list for PBXNativeTarget "Sample" */;
 			buildPhases = (
-				E080B80F89C34A25B3488E26 /* Check Pods Manifest.lock */,
+				E080B80F89C34A25B3488E26 /* 📦 Check Pods Manifest.lock */,
 				05E2127D19D4DB510098F589 /* Sources */,
 				05E2127E19D4DB510098F589 /* Frameworks */,
 				05E2127F19D4DB510098F589 /* Resources */,
-				F012A6F39E0149F18F564F50 /* Copy Pods Resources */,
+				F012A6F39E0149F18F564F50 /* 📦 Copy Pods Resources */,
-				FFF65E837E66ADA71296F0FF /* Embed Pods Frameworks */,
+				FFF65E837E66ADA71296F0FF /* 📦 Embed Pods Frameworks */,
 			);
 			buildRules = (
 			);
@@ -187,14 +193,14 @@
 /* End PBXResourcesBuildPhase section */
 
 /* Begin PBXShellScriptBuildPhase section */
-		E080B80F89C34A25B3488E26 /* Check Pods Manifest.lock */ = {
+		E080B80F89C34A25B3488E26 /* 📦 Check Pods Manifest.lock */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
 			);
 			inputPaths = (
 			);
-			name = "Check Pods Manifest.lock";
+			name = "📦 Check Pods Manifest.lock";
 			outputPaths = (
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -202,34 +208,34 @@
 			shellScript = "diff \"${PODS_ROOT}/../Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [[ $? != 0 ]] ; then\n    cat << EOM\nerror: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\nEOM\n    exit 1\nfi\n";
 			showEnvVarsInLog = 0;
 		};
-		F012A6F39E0149F18F564F50 /* Copy Pods Resources */ = {
+		F012A6F39E0149F18F564F50 /* 📦 Copy Pods Resources */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
 			);
 			inputPaths = (
 			);
-			name = "Copy Pods Resources";
+			name = "📦 Copy Pods Resources";
 			outputPaths = (
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods/Pods-resources.sh\"\n";
+			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods-Sample/Pods-Sample-resources.sh\"\n";
 			showEnvVarsInLog = 0;
 		};
-		FFF65E837E66ADA71296F0FF /* Embed Pods Frameworks */ = {
+		FFF65E837E66ADA71296F0FF /* 📦 Embed Pods Frameworks */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
 			);
 			inputPaths = (
 			);
-			name = "Embed Pods Frameworks";
+			name = "📦 Embed Pods Frameworks";
 			outputPaths = (
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods/Pods-frameworks.sh\"\n";
+			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods-Sample/Pods-Sample-frameworks.sh\"\n";
 			showEnvVarsInLog = 0;
 		};
 /* End PBXShellScriptBuildPhase section */
@@ -330,7 +336,7 @@
 		};
 		05E212A519D4DB510098F589 /* Debug */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = C068F1D3F0CC317E895FCDAB /* Pods.debug.xcconfig */;
+			baseConfigurationReference = 056298286C03B7760575CC56 /* Pods-Sample.debug.xcconfig */;
 			buildSettings = {
 				INFOPLIST_FILE = Sample/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
@@ -342,7 +348,7 @@
 		};
 		05E212A619D4DB510098F589 /* Release */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = 088AA6578212BE9BFBB07B70 /* Pods.release.xcconfig */;
+			baseConfigurationReference = A7F0013FBBCBEA0C9FB68986 /* Pods-Sample.release.xcconfig */;
 			buildSettings = {
 				INFOPLIST_FILE = Sample/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;

examples_extra/ASTraitCollection/Sample/KittenNode.m

@@ -130,13 +130,11 @@ static const CGFloat kInnerPadding = 10.0f;
 
 - (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
 {
-  ASTraitCollection *traitCollection = [self asyncTraitCollection];
-  
   ASStackLayoutSpec *stackSpec = [[ASStackLayoutSpec alloc] init];
   stackSpec.spacing = kInnerPadding;
-  stackSpec.children = @[_imageNode, _textNode];
+  [stackSpec setChildren:@[_imageNode, _textNode]];
   
-  if (traitCollection.horizontalSizeClass == UIUserInterfaceSizeClassRegular) {
+  if (self.asyncTraitCollection.horizontalSizeClass == UIUserInterfaceSizeClassRegular) {
     _imageNode.alignSelf = ASStackLayoutAlignSelfStart;
     stackSpec.direction = ASStackLayoutDirectionHorizontal;
   } else {