Improve Our Handling of Flow Layout Headers/Footers (#2939)

* Rejigger our flow layout supplementary support to make more sense.

* Support old protocol

* Update

* Update deprecation message

* Undeprecate insetForSection method, because it actually _does_ still work

* Update the tests

* Remove irrelevant junk

* Remove cast, add pragma

AsyncDisplayKit/ASCollectionView.h

@@ -416,33 +416,71 @@ ASDISPLAYNODE_DEPRECATED_MSG("Renamed to ASCollectionDelegate.")
 @end
 
 /**
- * Defines methods that let you coordinate with a `UICollectionViewFlowLayout` in combination with an `ASCollectionView`.
+ * Defines methods that let you coordinate a `UICollectionViewFlowLayout` in combination with an `ASCollectionNode`.
  */
-@protocol ASCollectionViewDelegateFlowLayout <ASCollectionDelegate>
+@protocol ASCollectionDelegateFlowLayout <ASCollectionDelegate>
 
 @optional
 
 /**
- * @discussion This method is deprecated and does nothing from 1.9.7 and up
- * Previously it applies the section inset to every cells within the corresponding section.
- * The expected behavior is to apply the section inset to the whole section rather than
- * shrinking each cell individually.
- * If you want this behavior, you can integrate your insets calculation into
- * `constrainedSizeForNodeAtIndexPath`
- * please file a github issue if you would like this to be restored.
+ * Asks the delegate for the inset that should be applied to the given section.
+ *
+ * @see the same method in UICollectionViewDelegate. 
  */
-- (UIEdgeInsets)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section ASDISPLAYNODE_DEPRECATED_MSG("This method does nothing for 1.9.7+ due to incorrect implementation previously, see the header file for more information.");
+- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;
+
+/**
+ * Asks the delegate for the size range that should be used to measure the header in the given flow layout section.
+ *
+ * @param collectionNode The sender.
+ * @param section The section.
+ *
+ * @return The size range for the header, or @c ASSizeRangeZero if there is no header in this section.
+ *
+ * If you want the header to completely determine its own size, return @c ASSizeRangeUnconstrained.
+ *
+ * @note Only the scrollable dimension of the returned size range will be used. In a vertical flow,
+ * only the height will be used. In a horizontal flow, only the width will be used. The other dimension
+ * will be constrained to fill the collection node.
+ *
+ * @discussion If you do not implement this method, ASDK will fall back to calling @c collectionView:layout:referenceSizeForHeaderInSection:
+ * and using that as the exact constrained size. If you don't implement that method, ASDK will read the @c headerReferenceSize from the layout.
+ */
+- (ASSizeRange)collectionNode:(ASCollectionNode *)collectionNode sizeRangeForHeaderInSection:(NSInteger)section;
+
+/**
+ * Asks the delegate for the size range that should be used to measure the footer in the given flow layout section.
+ *
+ * @param collectionNode The sender.
+ * @param section The section.
+ *
+ * @return The size range for the footer, or @c ASSizeRangeZero if there is no footer in this section.
+ *
+ * If you want the footer to completely determine its own size, return @c ASSizeRangeUnconstrained.
+ *
+ * @note Only the scrollable dimension of the returned size range will be used. In a vertical flow,
+ * only the height will be used. In a horizontal flow, only the width will be used. The other dimension
+ * will be constrained to fill the collection node.
+ *
+ * @discussion If you do not implement this method, ASDK will fall back to calling @c collectionView:layout:referenceSizeForFooterInSection:
+ * and using that as the exact constrained size. If you don't implement that method, ASDK will read the @c footerReferenceSize from the layout.
+ */
+- (ASSizeRange)collectionNode:(ASCollectionNode *)collectionNode sizeRangeForFooterInSection:(NSInteger)section;
 
 /**
  * Asks the delegate for the size of the header in the specified section.
  */
-- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;
+- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section ASDISPLAYNODE_DEPRECATED_MSG("Implement collectionNode:sizeRangeForHeaderInSection: instead.");
 
 /**
  * Asks the delegate for the size of the footer in the specified section.
  */
-- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section;
+- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section ASDISPLAYNODE_DEPRECATED_MSG("Implement collectionNode:sizeRangeForFooterInSection: instead.");
 
 @end
 
+ASDISPLAYNODE_DEPRECATED_MSG("Renamed to ASCollectionDelegateFlowLayout.")
+@protocol ASCollectionViewDelegateFlowLayout <ASCollectionDelegateFlowLayout>
+@end
+
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASCollectionView.mm

@@ -138,7 +138,7 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
 #pragma mark -
 #pragma mark ASCollectionView.
 
-@interface ASCollectionView () <ASRangeControllerDataSource, ASRangeControllerDelegate, ASCollectionDataControllerSource, ASCellNodeInteractionDelegate, ASDelegateProxyInterceptor, ASBatchFetchingScrollView, ASDataControllerEnvironmentDelegate, ASCALayerExtendedDelegate> {
+@interface ASCollectionView () <ASRangeControllerDataSource, ASRangeControllerDelegate, ASCollectionDataControllerSource, ASCellNodeInteractionDelegate, ASDelegateProxyInterceptor, ASBatchFetchingScrollView, ASDataControllerEnvironmentDelegate, ASCALayerExtendedDelegate, UICollectionViewDelegateFlowLayout> {
   ASCollectionViewProxy *_proxyDataSource;
   ASCollectionViewProxy *_proxyDelegate;
   
@@ -927,6 +927,16 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
   return [[self nodeForItemAtIndexPath:indexPath] calculatedSize];
 }
 
+- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
+{
+  return [self supplementaryNodeForElementKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:section]].calculatedSize;
+}
+
+- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
+{
+  return [self supplementaryNodeForElementKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:section]].calculatedSize;
+}
+
 - (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
 {
   UICollectionReusableView *view = [self dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:kReuseIdentifier forIndexPath:indexPath];
@@ -936,8 +946,6 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
   return view;
 }
 
-
-
 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
 {
   _ASCollectionViewCell *cell = [self dequeueReusableCellWithReuseIdentifier:kReuseIdentifier forIndexPath:indexPath];

AsyncDisplayKit/ASPagerNode.m

@@ -18,7 +18,7 @@
 #import "ASCellNode.h"
 #import "ASCollectionView+Undeprecated.h"
 
-@interface ASPagerNode () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor>
+@interface ASPagerNode () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionDelegateFlowLayout, ASDelegateProxyInterceptor>
 {
   ASPagerFlowLayout *_flowLayout;
 

AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.m

@@ -24,7 +24,9 @@
  
 @implementation ASCollectionViewFlowLayoutInspector {
   struct {
+    unsigned int implementsSizeRangeForHeader:1;
     unsigned int implementsReferenceSizeForHeader:1;
+    unsigned int implementsSizeRangeForFooter:1;
     unsigned int implementsReferenceSizeForFooter:1;
     unsigned int implementsConstrainedSizeForNodeAtIndexPathDeprecated:1;
     unsigned int implementsConstrainedSizeForItemAtIndexPath:1;
@@ -53,7 +55,9 @@
   if (delegate == nil) {
     memset(&_delegateFlags, 0, sizeof(_delegateFlags));
   } else {
+    _delegateFlags.implementsSizeRangeForHeader = [delegate respondsToSelector:@selector(collectionNode:sizeRangeForHeaderInSection:)];
     _delegateFlags.implementsReferenceSizeForHeader = [delegate respondsToSelector:@selector(collectionView:layout:referenceSizeForHeaderInSection:)];
+    _delegateFlags.implementsSizeRangeForFooter = [delegate respondsToSelector:@selector(collectionNode:sizeRangeForFooterInSection:)];
     _delegateFlags.implementsReferenceSizeForFooter = [delegate respondsToSelector:@selector(collectionView:layout:referenceSizeForFooterInSection:)];
     _delegateFlags.implementsConstrainedSizeForNodeAtIndexPathDeprecated = [delegate respondsToSelector:@selector(collectionView:constrainedSizeForNodeAtIndexPath:)];
     _delegateFlags.implementsConstrainedSizeForItemAtIndexPath = [delegate respondsToSelector:@selector(collectionNode:constrainedSizeForItemAtIndexPath:)];
@@ -84,19 +88,52 @@
 
 - (ASSizeRange)collectionView:(ASCollectionView *)collectionView constrainedSizeForSupplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
 {
-  CGSize constrainedSize;
-  CGSize supplementarySize = [self sizeForSupplementaryViewOfKind:kind inSection:indexPath.section collectionView:collectionView];
-  if (_layout.scrollDirection == UICollectionViewScrollDirectionVertical) {
-    constrainedSize = CGSizeMake(CGRectGetWidth(collectionView.bounds), supplementarySize.height);
+  ASSizeRange result = ASSizeRangeZero;
+  if (ASObjectIsEqual(kind, UICollectionElementKindSectionHeader)) {
+    if (_delegateFlags.implementsSizeRangeForHeader) {
+      result = [[self delegateForCollectionView:collectionView] collectionNode:collectionView.collectionNode sizeRangeForHeaderInSection:indexPath.section];
+    } else if (_delegateFlags.implementsReferenceSizeForHeader) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+      CGSize exactSize = [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForHeaderInSection:indexPath.section];
+#pragma clang diagnostic pop
+      result = ASSizeRangeMake(exactSize);
+    } else {
+      result = ASSizeRangeMake(_layout.headerReferenceSize);
+    }
+  } else if (ASObjectIsEqual(kind, UICollectionElementKindSectionFooter)) {
+    if (_delegateFlags.implementsSizeRangeForFooter) {
+      result = [[self delegateForCollectionView:collectionView] collectionNode:collectionView.collectionNode sizeRangeForFooterInSection:indexPath.section];
+    } else if (_delegateFlags.implementsReferenceSizeForFooter) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+      CGSize exactSize = [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForFooterInSection:indexPath.section];
+#pragma clang diagnostic pop
+      result = ASSizeRangeMake(exactSize);
+    } else {
+      result = ASSizeRangeMake(_layout.footerReferenceSize);
+    }
   } else {
-    constrainedSize = CGSizeMake(supplementarySize.width, CGRectGetHeight(collectionView.bounds));
+    ASDisplayNodeFailAssert(@"Unexpected supplementary kind: %@", kind);
+    return ASSizeRangeZero;
   }
-  return ASSizeRangeMake(CGSizeZero, constrainedSize);
+
+  if (_layout.scrollDirection == UICollectionViewScrollDirectionVertical) {
+    result.min.width = result.max.width = CGRectGetWidth(collectionView.bounds);
+  } else {
+    result.min.height = result.max.height = CGRectGetHeight(collectionView.bounds);
+  }
+  return result;
 }
 
 - (NSUInteger)collectionView:(ASCollectionView *)collectionView supplementaryNodesOfKind:(NSString *)kind inSection:(NSUInteger)section
 {
-  return [self layoutHasSupplementaryViewOfKind:kind inSection:section collectionView:collectionView] ? 1 : 0;
+  ASSizeRange constraint = [self collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:kind atIndexPath:[NSIndexPath indexPathForItem:0 inSection:section]];
+  if (_layout.scrollDirection == UICollectionViewScrollDirectionVertical) {
+    return (constraint.max.height > 0 ? 1 : 0);
+  } else {
+    return (constraint.max.width > 0 ? 1 : 0);
+  }
 }
 
 - (ASScrollDirection)scrollableDirections
@@ -106,43 +143,9 @@
 
 #pragma mark - Private helpers
 
-- (CGSize)sizeForSupplementaryViewOfKind:(NSString *)kind inSection:(NSUInteger)section collectionView:(ASCollectionView *)collectionView
+- (id<ASCollectionDelegateFlowLayout>)delegateForCollectionView:(ASCollectionView *)collectionView
 {
-  if (ASObjectIsEqual(kind, UICollectionElementKindSectionHeader)) {
-    if (_delegateFlags.implementsReferenceSizeForHeader) {
-      return [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForHeaderInSection:section];
-    } else {
-      return [self.layout headerReferenceSize];
-    }
-  } else if (ASObjectIsEqual(kind, UICollectionElementKindSectionFooter)) {
-    if (_delegateFlags.implementsReferenceSizeForFooter) {
-      return [[self delegateForCollectionView:collectionView] collectionView:collectionView layout:_layout referenceSizeForFooterInSection:section];
-    } else {
-      return [self.layout footerReferenceSize];
-    }
-  } else {
-    return CGSizeZero;
-  }
-}
-
-- (BOOL)layoutHasSupplementaryViewOfKind:(NSString *)kind inSection:(NSUInteger)section collectionView:(ASCollectionView *)collectionView
-{
-  CGSize size = [self sizeForSupplementaryViewOfKind:kind inSection:section collectionView:collectionView];
-  return [self usedLayoutValueForSize:size] > 0;
-}
-
-- (CGFloat)usedLayoutValueForSize:(CGSize)size
-{
-  if (_layout.scrollDirection == UICollectionViewScrollDirectionVertical) {
-    return size.height;
-  } else {
-    return size.width;
-  }
-}
-
-- (id<ASCollectionViewDelegateFlowLayout>)delegateForCollectionView:(ASCollectionView *)collectionView
-{
-  return (id<ASCollectionViewDelegateFlowLayout>)collectionView.asyncDelegate;
+  return (id<ASCollectionDelegateFlowLayout>)collectionView.asyncDelegate;
 }
 
 @end

AsyncDisplayKit/Details/ASDelegateProxy.m

@@ -68,6 +68,8 @@
           // handled by ASCollectionView node<->cell machinery
           selector == @selector(collectionView:cellForItemAtIndexPath:) ||
           selector == @selector(collectionView:layout:sizeForItemAtIndexPath:) ||
+          selector == @selector(collectionView:layout:referenceSizeForHeaderInSection:) ||
+          selector == @selector(collectionView:layout:referenceSizeForFooterInSection:) ||
           selector == @selector(collectionView:viewForSupplementaryElementOfKind:atIndexPath:) ||
           
           // Selection, highlighting, menu

AsyncDisplayKit/Layout/ASDimension.h

@@ -201,6 +201,16 @@ typedef struct {
   CGSize max;
 } ASSizeRange;
 
+/**
+ * A size range with all dimensions zero.
+ */
+extern ASSizeRange const ASSizeRangeZero;
+
+/**
+ * A size range from zero to infinity in both directions.
+ */
+extern ASSizeRange const ASSizeRangeUnconstrained;
+
 /**
  * Creates an ASSizeRange with provided min and max size.
  */

AsyncDisplayKit/Layout/ASDimension.mm

@@ -61,6 +61,10 @@ ASLayoutSize const ASLayoutSizeAuto = {ASDimensionAuto, ASDimensionAuto};
 
 #pragma mark - ASSizeRange
 
+ASSizeRange const ASSizeRangeZero = {};
+
+ASSizeRange const ASSizeRangeUnconstrained = { {0, 0}, { INFINITY, INFINITY }};
+
 struct _Range {
   CGFloat min;
   CGFloat max;

AsyncDisplayKitTests/ASCollectionViewFlowLayoutInspectorTests.m

@@ -11,6 +11,7 @@
 #import <XCTest/XCTest.h>
 #import <UIKit/UIKit.h>
 #import <OCMock/OCMock.h>
+#import "ASXCTExtensions.h"
 
 #import "ASCollectionView.h"
 #import "ASCollectionNode.h"
@@ -82,7 +83,7 @@
 /**
  * Test Delegate for Header Reference Size Implementation
  */
-@interface HeaderReferenceSizeTestDelegate : NSObject <ASCollectionViewDelegateFlowLayout>
+@interface HeaderReferenceSizeTestDelegate : NSObject <ASCollectionDelegateFlowLayout>
 
 @end
 
@@ -98,7 +99,7 @@
 /**
  * Test Delegate for Footer Reference Size Implementation
  */
-@interface FooterReferenceSizeTestDelegate : NSObject <ASCollectionViewDelegateFlowLayout>
+@interface FooterReferenceSizeTestDelegate : NSObject <ASCollectionDelegateFlowLayout>
 
 @end
 
@@ -144,8 +145,9 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(collectionView.bounds.size.width, 125.0));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the values returned in the delegate implementation");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(collectionView.bounds.size.width, 125.0));
+
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the values returned in the delegate implementation");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -166,8 +168,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(collectionView.bounds.size.width, 125.0));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the values returned in the delegate implementation");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(collectionView.bounds.size.width, 125.0));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the values returned in the delegate implementation");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -189,8 +191,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(collectionView.bounds.size.width, 125.0));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the size set on the layout");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(collectionView.bounds.size.width, 125.0));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the size set on the layout");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -210,8 +212,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(collectionView.bounds.size.width, 125.0));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the size set on the layout");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(collectionView.bounds.size.width, 125.0));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the size set on the layout");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -234,8 +236,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(125.0, collectionView.bounds.size.height));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the values returned in the delegate implementation");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(125.0, collectionView.bounds.size.height));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the values returned in the delegate implementation");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -256,8 +258,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(125.0, collectionView.bounds.size.height));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the values returned in the delegate implementation");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(125.0, collectionView.bounds.size.height));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the values returned in the delegate implementation");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -279,8 +281,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(125.0, collectionView.bounds.size.width));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the size set on the layout");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(125.0, collectionView.bounds.size.width));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the size set on the layout");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;
@@ -300,8 +302,8 @@
   
   ASCollectionViewFlowLayoutInspector *inspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:collectionView flowLayout:layout];
   ASSizeRange size = [inspector collectionView:collectionView constrainedSizeForSupplementaryNodeOfKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
-  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeZero, CGSizeMake(125.0, collectionView.bounds.size.height));
-  XCTAssert(CGSizeEqualToSize(size.min, sizeCompare.min) && CGSizeEqualToSize(size.max, sizeCompare.max), @"should have a size constrained by the size set on the layout");
+  ASSizeRange sizeCompare = ASSizeRangeMake(CGSizeMake(125.0, collectionView.bounds.size.height));
+  ASXCTAssertEqualSizeRanges(size, sizeCompare, @"should have a size constrained by the size set on the layout");
   
   collectionView.asyncDataSource = nil;
   collectionView.asyncDelegate = nil;

examples/CatDealsCollectionView/Sample/BlurbNode.h

@@ -22,6 +22,4 @@
  */
 @interface BlurbNode : ASCellNode
 
-+ (CGFloat)desiredHeightForWidth:(CGFloat)width;
-
 @end

examples/CatDealsCollectionView/Sample/BlurbNode.m

@@ -39,10 +39,6 @@ static CGFloat kTextPadding = 10.0f;
 #pragma mark -
 #pragma mark ASCellNode.
 
-+ (CGFloat)desiredHeightForWidth:(CGFloat)width {
-  return kFixedHeight;
-}
-
 - (instancetype)init
 {
   if (!(self = [super init]))

examples/CatDealsCollectionView/Sample/LoadingNode.h

@@ -21,6 +21,4 @@
 
 @interface LoadingNode : ASCellNode
 
-+ (CGFloat)desiredHeightForWidth:(CGFloat)width;
-
 @end

examples/CatDealsCollectionView/Sample/LoadingNode.m

@@ -39,10 +39,6 @@ static CGFloat kFixedHeight = 200.0f;
 #pragma mark -
 #pragma mark ASCellNode.
 
-+ (CGFloat)desiredHeightForWidth:(CGFloat)width {
-  return kFixedHeight;
-}
-
 - (instancetype)init
 {
   if (!(self = [super init]))
@@ -61,10 +57,6 @@ static CGFloat kFixedHeight = 200.0f;
   return self;
 }
 
-- (void)layout {
-  [super layout];
-}
-
 - (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
 {
   ASCenterLayoutSpec *centerSpec = [[ASCenterLayoutSpec alloc] init];

examples/CatDealsCollectionView/Sample/ViewController.m

@@ -29,7 +29,7 @@ static const NSInteger kBatchSize = 20;
 static const CGFloat kHorizontalSectionPadding = 10.0f;
 static const CGFloat kVerticalSectionPadding = 20.0f;
 
-@interface ViewController () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionViewDelegateFlowLayout>
+@interface ViewController () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionDelegateFlowLayout>
 {
   ASCollectionNode *_collectionNode;
   NSMutableArray *_data;
@@ -203,27 +203,24 @@ static const CGFloat kVerticalSectionPadding = 20.0f;
   }];
 }
 
-#pragma mark - ASCollectionViewDelegateFlowLayout
+#pragma mark - ASCollectionDelegateFlowLayout
 
-- (UIEdgeInsets)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
-  return UIEdgeInsetsMake(kVerticalSectionPadding, kHorizontalSectionPadding, kVerticalSectionPadding, kHorizontalSectionPadding);
-}
-
-- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
+- (ASSizeRange)collectionNode:(ASCollectionNode *)collectionNode referenceConstrainedSizeForHeaderInSection:(NSInteger)section
+{
   if (section == 0) {
-    CGFloat width = CGRectGetWidth(self.view.frame) - 2 * kHorizontalSectionPadding;
-    return CGSizeMake(width, [BlurbNode desiredHeightForWidth:width]);
+    return ASSizeRangeUnconstrained;
+  } else {
+    return ASSizeRangeZero;
   }
-  return CGSizeZero;
 }
 
-- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {
+- (ASSizeRange)collectionNode:(ASCollectionNode *)collectionNode referenceConstrainedSizeForFooterInSection:(NSInteger)section
+{
   if (section == 0) {
-    CGFloat width = CGRectGetWidth(self.view.frame);
-    return CGSizeMake(width, [LoadingNode desiredHeightForWidth:width]);
+    return ASSizeRangeUnconstrained;
+  } else {
+    return ASSizeRangeZero;
   }
-  return CGSizeZero;
 }
 
-
 @end