Respond to supplementary node feedback

AsyncDisplayKit/ASCollectionView.h

@@ -90,7 +90,7 @@
  * collection view layout subclasses will need to provide their own implementation of an inspector object for their
  * supplementary views to be compatible with `ASCollectionView`'s supplementary node support.
  */
-@property (nonatomic, weak) id<ASCollectionViewLayoutInspecting> layoutDelegate;
+@property (nonatomic, weak) id<ASCollectionViewLayoutInspecting> layoutInspector;
 
 /**
  *  Perform a batch of updates asynchronously, optionally disabling all animations in the batch. This method must be called from the main thread. 

AsyncDisplayKit/ASCollectionView.mm

@@ -153,7 +153,7 @@ @interface ASCollectionView () <ASRangeControllerDelegate, ASDataControllerSourc
   CGSize _maxSizeForNodesConstrainedSize;
   BOOL _ignoreMaxSizeChange;
 
-  NSMutableArray *_registeredSupplementaryKinds;
+  NSMutableSet *_registeredSupplementaryKinds;
 
   /**
    * If YES, the `UICollectionView` will reload its data on next layout pass so we should not forward any updates to it.
@@ -229,10 +229,10 @@ - (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionVi
   // Register the default layout inspector delegate for flow layouts only, custom layouts
   // will need to roll their own ASCollectionViewLayoutInspecting implementation and set a layout delegate
   if ([layout asdk_isFlowLayout]) {
-    _layoutDelegate = [self flowLayoutInspector];
+    _layoutInspector = [self flowLayoutInspector];
   }
 
-  _registeredSupplementaryKinds = [NSMutableArray array];
+  _registeredSupplementaryKinds = [NSMutableSet set];
 
   self.backgroundColor = [UIColor whiteColor];
 
@@ -256,6 +256,7 @@ - (ASCollectionViewFlowLayoutInspector *)flowLayoutInspector
 {
     if (_flowLayoutInspector == nil) {
         UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)self.collectionViewLayout;
+        ASDisplayNodeAssertNotNil(layout, @"Collection view layout must be a flow layout to use the built-in inspector");
         _flowLayoutInspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:self
                                                                                         flowLayout:layout];
     }
@@ -333,16 +334,7 @@ - (void)setAsyncDelegate:(id<ASCollectionViewDelegate>)asyncDelegate
     _asyncDelegateImplementsInsetSection = ([_asyncDelegate respondsToSelector:@selector(collectionView:layout:insetForSectionAtIndex:)] ? 1 : 0);
   }
 
-  [_flowLayoutInspector cacheSelectorsForCollectionView:self];
-}
-
-- (void)setCollectionViewLayout:(UICollectionViewLayout *)collectionViewLayout
-{
-  [super setCollectionViewLayout:collectionViewLayout];
-  if ([collectionViewLayout asdk_isFlowLayout]) {
-    _flowLayoutInspector = nil;
-    _layoutDelegate = [self flowLayoutInspector];
-  }
+  [_layoutInspector didChangeCollectionViewDelegate:asyncDelegate];
 }
 
 - (void)setTuningParameters:(ASRangeTuningParameters)tuningParameters forRangeType:(ASLayoutRangeType)rangeType
@@ -745,25 +737,25 @@ - (ASCellNode *)dataController:(ASCollectionDataController *)dataController supp
 
 - (NSArray *)supplementaryNodeKindsInDataController:(ASCollectionDataController *)dataController
 {
-  return _registeredSupplementaryKinds;
+  return [_registeredSupplementaryKinds allObjects];
 }
 
 - (ASSizeRange)dataController:(ASCollectionDataController *)dataController constrainedSizeForSupplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
 {
-  ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
-  return [_layoutDelegate collectionView:self constrainedSizeForSupplementaryNodeOfKind:kind atIndexPath:indexPath];
+  ASDisplayNodeAssert(_layoutInspector != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
+  return [_layoutInspector collectionView:self constrainedSizeForSupplementaryNodeOfKind:kind atIndexPath:indexPath];
 }
 
 - (NSUInteger)dataController:(ASCollectionDataController *)dataController supplementaryNodesOfKind:(NSString *)kind inSection:(NSUInteger)section
 {
-  ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
-  return [_layoutDelegate collectionView:self supplementaryNodesOfKind:kind inSection:section];
+  ASDisplayNodeAssert(_layoutInspector != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
+  return [_layoutInspector collectionView:self supplementaryNodesOfKind:kind inSection:section];
 }
 
 - (NSUInteger)dataController:(ASCollectionDataController *)dataController numberOfSectionsForSupplementaryNodeOfKind:(NSString *)kind;
 {
-  ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
-  return [_layoutDelegate collectionView:self numberOfSectionsForSupplementaryNodeOfKind:kind];
+  ASDisplayNodeAssert(_layoutInspector != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
+  return [_layoutInspector collectionView:self numberOfSectionsForSupplementaryNodeOfKind:kind];
 }
 
 #pragma mark - ASRangeControllerDelegate.

AsyncDisplayKit/Details/ASCollectionDataController.mm

@@ -61,7 +61,7 @@ - (void)willReloadData
     NSUInteger sectionCount = [self.collectionDataSource dataController:self numberOfSectionsForSupplementaryNodeOfKind:kind];
     NSMutableArray *sections = [NSMutableArray arrayWithCapacity:sectionCount];
     for (int i = 0; i < sectionCount; i++) {
-      [sections addObject:[[NSMutableArray alloc] init]];
+      [sections addObject:[NSMutableArray array]];
     }
     [self insertSections:sections ofKind:kind atIndexSet:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, sectionCount)] completion:nil];
 

AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.h

@@ -11,6 +11,7 @@
 #import <AsyncDisplayKit/ASDimension.h>
 
 @class ASCollectionView;
+@protocol ASCollectionViewDelegate;
 
 @protocol ASCollectionViewLayoutInspecting <NSObject>
 
@@ -29,6 +30,13 @@
  */
 - (NSUInteger)collectionView:(ASCollectionView *)collectionView supplementaryNodesOfKind:(NSString *)kind inSection:(NSUInteger)section;
 
+/**
+ * Allow the inspector to respond to delegate changes.
+ *
+ * @discussion A great time to update perform selector caches!
+ */
+- (void)didChangeCollectionViewDelegate:(id<ASCollectionViewDelegate>)delegate;
+
 @end
 
 @interface ASCollectionViewFlowLayoutInspector : NSObject <ASCollectionViewLayoutInspecting>
@@ -37,6 +45,4 @@
 
 - (instancetype)initWithCollectionView:(ASCollectionView *)collectionView flowLayout:(UICollectionViewFlowLayout *)flowLayout;
 
-- (void)cacheSelectorsForCollectionView:(ASCollectionView *)collectionView;
-
 @end

AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.m

@@ -11,6 +11,8 @@
 #import "ASCollectionViewFlowLayoutInspector.h"
 
 #import "ASCollectionView.h"
+#import "ASAssert.h"
+#import "ASEqualityHelpers.h"
 
 @implementation ASCollectionViewFlowLayoutInspector {
   BOOL _delegateImplementsReferenceSizeForHeader;
@@ -24,24 +26,24 @@ - (instancetype)initWithCollectionView:(ASCollectionView *)collectionView flowLa
   self = [super init];
 
   if (flowLayout == nil) {
-    return nil;
+    ASDisplayNodeAssert(NO, @"Should never create a layout inspector without a layout");
   }
 
   if (self != nil) {
-    [self cacheSelectorsForCollectionView:collectionView];
+    [self didChangeCollectionViewDelegate:collectionView.asyncDelegate];
     _layout = flowLayout;
   }
   return self;
 }
 
-- (void)cacheSelectorsForCollectionView:(ASCollectionView *)collectionView
+- (void)didChangeCollectionViewDelegate:(id<ASCollectionViewDelegate>)delegate;
 {
-  if (collectionView == nil) {
-    _delegateImplementsReferenceSizeForHeader = nil;
-    _delegateImplementsReferenceSizeForFooter = nil;
+  if (delegate == nil) {
+    _delegateImplementsReferenceSizeForHeader = NO;
+    _delegateImplementsReferenceSizeForFooter = NO;
   } else {
-    _delegateImplementsReferenceSizeForHeader = [[self delegateForCollectionView:collectionView] respondsToSelector:@selector(collectionView:layout:referenceSizeForHeaderInSection:)];
-    _delegateImplementsReferenceSizeForFooter = [[self delegateForCollectionView:collectionView] respondsToSelector:@selector(collectionView:layout:referenceSizeForFooterInSection:)];
+    _delegateImplementsReferenceSizeForHeader = [delegate respondsToSelector:@selector(collectionView:layout:referenceSizeForHeaderInSection:)];
+    _delegateImplementsReferenceSizeForFooter = [delegate respondsToSelector:@selector(collectionView:layout:referenceSizeForFooterInSection:)];
   }
 }
 
@@ -77,13 +79,13 @@ - (NSUInteger)collectionView:(ASCollectionView *)collectionView supplementaryNod
 
 - (CGSize)sizeForSupplementaryViewOfKind:(NSString *)kind inSection:(NSUInteger)section collectionView:(ASCollectionView *)collectionView
 {
-  if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
+  if (ASObjectIsEqual(kind, UICollectionElementKindSectionHeader)) {
     if (_delegateImplementsReferenceSizeForHeader) {
       return [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForHeaderInSection:section];
     } else {
       return [self.layout headerReferenceSize];
     }
-  } else if ([kind isEqualToString:UICollectionElementKindSectionFooter]) {
+  } else if (ASObjectIsEqual(kind, UICollectionElementKindSectionFooter)) {
     if (_delegateImplementsReferenceSizeForFooter) {
       return [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForFooterInSection:section];
     } else {

AsyncDisplayKit/Details/ASDataController+Subclasses.h

@@ -74,8 +74,8 @@
 /**
  * Notifies the subclass to perform any work needed before the data controller is reloaded entirely
  *
- * @discussion This method will be performed before the data controller enters its editing queue, usually on the main
- * thread. The data source is locked at this point and accessing it is safe. Use this method to set up any nodes or
+ * @discussion This method will be performed before the data controller enters its editing queue.
+ * The data source is locked at this point and accessing it is safe. Use this method to set up any nodes or
  * data stores before entering into editing the backing store on a background thread.
  */
  - (void)prepareForReloadData;
@@ -92,8 +92,8 @@
 /**
  * Notifies the subclass to perform setup before sections are inserted in the data controller
  *
- * @discussion This method will be performed before the data controller enters its editing queue, usually on the main
- * thread. The data source is locked at this point and accessing it is safe. Use this method to set up any nodes or
+ * @discussion This method will be performed before the data controller enters its editing queue.
+ * The data source is locked at this point and accessing it is safe. Use this method to set up any nodes or
  * data stores before entering into editing the backing store on a background thread.
  *
  * @param sections Indices of sections to be inserted

AsyncDisplayKit/Details/ASDataController.mm

@@ -15,6 +15,7 @@
 #import "ASDisplayNode.h"
 #import "ASMultidimensionalArrayUtils.h"
 #import "ASDisplayNodeInternal.h"
+#import "ASLayout.h"
 
 //#define LOG(...) NSLog(__VA_ARGS__)
 #define LOG(...)
@@ -185,8 +186,9 @@ - (void)_layoutNodes:(NSArray *)nodes ofKind:(NSString *)kind atIndexPaths:(NSAr
   dispatch_group_wait(layoutGroup, DISPATCH_TIME_FOREVER);
   free(nodeBoundSizes);
 
-  if (completionBlock)
+  if (completionBlock) {
     completionBlock(nodes, indexPaths);
+  }
 }
 
 - (ASSizeRange)constrainedSizeForNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
@@ -218,8 +220,10 @@ - (void)insertNodes:(NSArray *)nodes ofKind:(NSString *)kind atIndexPaths:(NSArr
 
 - (void)deleteNodesOfKind:(NSString *)kind atIndexPaths:(NSArray *)indexPaths completion:(void (^)(NSArray *nodes, NSArray *indexPaths))completionBlock
 {
-  if (indexPaths.count == 0)
+  if (indexPaths.count == 0) {
     return;
+  }
+
   LOG(@"_deleteNodesAtIndexPaths:%@ ofKind:%@, full index paths in _editingNodes = %@", indexPaths, kind, ASIndexPathsForMultidimensionalArray(_editingNodes[kind]));
   NSMutableArray *editingNodes = _editingNodes[kind];
   ASDeleteElementsInMultidimensionalArrayAtIndexPaths(editingNodes, indexPaths);
@@ -818,8 +822,8 @@ - (void)_relayoutNodesOfKind:(NSString *)kind
       [section enumerateObjectsUsingBlock:^(ASCellNode *node, NSUInteger rowIndex, BOOL *stop) {
         NSIndexPath *indexPath = [NSIndexPath indexPathForRow:rowIndex inSection:sectionIndex];
         ASSizeRange constrainedSize = [self constrainedSizeForNodeOfKind:kind atIndexPath:indexPath];
-        [node measureWithSizeRange:constrainedSize];
-        node.frame = CGRectMake(0.0f, 0.0f, node.calculatedSize.width, node.calculatedSize.height);
+        ASLayout *layout = [node measureWithSizeRange:constrainedSize];
+        node.frame = CGRectMake(0.0f, 0.0f, layout.size.width, layout.size.height);
       }];
     }];
   }];
@@ -849,7 +853,7 @@ - (void)moveRowAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)n
 
 - (NSArray *)indexPathsForEditingNodesOfKind:(NSString *)kind
 {
-  return _editingNodes[kind] != nil ? ASIndexPathsForMultidimensionalArray(_editingNodes[kind]) : [NSArray array];
+  return _editingNodes[kind] != nil ? ASIndexPathsForMultidimensionalArray(_editingNodes[kind]) : nil;
 }
 
 - (NSMutableArray *)editingNodesOfKind:(NSString *)kind

AsyncDisplayKitTests/ASCollectionViewTests.m

@@ -91,15 +91,15 @@ - (void)testThatItSetsALayoutInspectorForFlowLayouts
 {
   UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
   ASCollectionView *collectionView = [[ASCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
-  XCTAssert(collectionView.layoutDelegate != nil, @"should automatically set a layout delegate for flow layouts");
-  XCTAssert([collectionView.layoutDelegate isKindOfClass:[ASCollectionViewFlowLayoutInspector class]], @"should have a flow layout inspector by default");
+  XCTAssert(collectionView.layoutInspector != nil, @"should automatically set a layout delegate for flow layouts");
+  XCTAssert([collectionView.layoutInspector isKindOfClass:[ASCollectionViewFlowLayoutInspector class]], @"should have a flow layout inspector by default");
 }
 
 - (void)testThatItDoesNotSetALayoutInspectorForCustomLayouts
 {
   UICollectionViewLayout *layout = [[UICollectionViewLayout alloc] init];
   ASCollectionView *collectionView = [[ASCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
-  XCTAssert(collectionView.layoutDelegate == nil, @"should not set a layout delegate for custom layouts");
+  XCTAssert(collectionView.layoutInspector == nil, @"should not set a layout delegate for custom layouts");
 }
 
 - (void)testThatRegisteringASupplementaryNodeStoresItForIntrospection