Added header

CarouselCollectionViewLayout.xcodeproj/project.pbxproj

@@ -18,9 +18,9 @@
 		43078F6A197BD9FD0025ECBF /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 43078F4F197BD9FD0025ECBF /* Foundation.framework */; };
 		43078F6B197BD9FD0025ECBF /* UIKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 43078F53197BD9FD0025ECBF /* UIKit.framework */; };
 		43078F75197BD9FD0025ECBF /* CarouselLayoutTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 43078F74197BD9FD0025ECBF /* CarouselLayoutTests.m */; };
-		B27A913BFA596301C18A9698 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m in Sources */ = {isa = PBXBuildFile; fileRef = B27A966E3FC40E0996945370 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */; };
 		B27A94D3F3143E09C71A455F /* PBDCarouselCollectionViewLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = B27A9F7C36FCCD1A28D832CE /* PBDCarouselCollectionViewLayout.m */; };
 		B27A96663940BFABA727FAC0 /* CarouselCollectionViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = B27A954C849FCCE3E366BB70 /* CarouselCollectionViewController.m */; };
+		B27A9AA6B040EA3A34248564 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m in Sources */ = {isa = PBXBuildFile; fileRef = B27A96430E04235FEF987259 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -51,10 +51,11 @@
 		439841EE1C47E28600719676 /* CarouselCollectionViewLayoutTests-Prefix.pch */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "CarouselCollectionViewLayoutTests-Prefix.pch"; sourceTree = "<group>"; };
 		439841EF1C47E28600719676 /* CarouselCollectionViewLayoutTests-Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = "CarouselCollectionViewLayoutTests-Info.plist"; sourceTree = "<group>"; };
 		B27A900D6191713D16CE53F3 /* CarouselCollectionViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = CarouselCollectionViewController.h; sourceTree = "<group>"; };
-		B27A92408CE32697829986F2 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h; sourceTree = "<group>"; };
 		B27A92B41B76EEAE062EF3A4 /* PBDCarouselCollectionViewLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBDCarouselCollectionViewLayout.h; sourceTree = "<group>"; };
 		B27A954C849FCCE3E366BB70 /* CarouselCollectionViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = CarouselCollectionViewController.m; sourceTree = "<group>"; };
-		B27A966E3FC40E0996945370 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m; sourceTree = "<group>"; };
+		B27A96430E04235FEF987259 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m; sourceTree = "<group>"; };
+		B27A9D603D06657B3AFAFEF8 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h; sourceTree = "<group>"; };
+		B27A9E68A4FA40042C24F895 /* PBDCarouselCollectionViewLayoutPropertiesCache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBDCarouselCollectionViewLayoutPropertiesCache.h; sourceTree = "<group>"; };
 		B27A9F7C36FCCD1A28D832CE /* PBDCarouselCollectionViewLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBDCarouselCollectionViewLayout.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -179,21 +180,22 @@
 			path = Classes;
 			sourceTree = "<group>";
 		};
-		B27A981EA672C5FE98221A8F /* Helpers */ = {
+		B27A9945B6C04DDA15B37511 /* Internal */ = {
 			isa = PBXGroup;
 			children = (
-				B27A966E3FC40E0996945370 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */,
-				B27A92408CE32697829986F2 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h */,
+				B27A96430E04235FEF987259 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m */,
+				B27A9D603D06657B3AFAFEF8 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h */,
+				B27A9E68A4FA40042C24F895 /* PBDCarouselCollectionViewLayoutPropertiesCache.h */,
 			);
-			path = Helpers;
+			path = Internal;
 			sourceTree = "<group>";
 		};
 		B27A9E6A011735C5D4F66808 /* Lib */ = {
 			isa = PBXGroup;
 			children = (
 				B27A92B41B76EEAE062EF3A4 /* PBDCarouselCollectionViewLayout.h */,
 				B27A9F7C36FCCD1A28D832CE /* PBDCarouselCollectionViewLayout.m */,
-				B27A981EA672C5FE98221A8F /* Helpers */,
+				B27A9945B6C04DDA15B37511 /* Internal */,
 			);
 			path = Lib;
 			sourceTree = "<group>";
@@ -296,7 +298,7 @@
 				43078F5C197BD9FD0025ECBF /* main.m in Sources */,
 				B27A94D3F3143E09C71A455F /* PBDCarouselCollectionViewLayout.m in Sources */,
 				B27A96663940BFABA727FAC0 /* CarouselCollectionViewController.m in Sources */,
-				B27A913BFA596301C18A9698 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m in Sources */,
+				B27A9AA6B040EA3A34248564 /* PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

CarouselCollectionViewLayout/Classes/Demo/CarouselCollectionViewController.m

@@ -12,6 +12,7 @@ - (id)init {
     PBDCarouselCollectionViewLayout *layout = [[PBDCarouselCollectionViewLayout alloc] init];
     layout.itemSize = CGSizeMake(280, 240);
     layout.interItemSpace = 20;
+    layout.headerSize = CGSizeMake(100, 490);
     self = [super initWithCollectionViewLayout:layout];
     if (self) {
 
@@ -27,6 +28,9 @@ - (void)viewDidLoad {
 
     self.collectionView.decelerationRate = UIScrollViewDecelerationRateFast;
     [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"Cell"];
+    [self.collectionView registerClass:[UICollectionReusableView class]
+            forSupplementaryViewOfKind:PBDCollectionElementKindSectionHeader
+                   withReuseIdentifier:@"Header"];
 
     self.collectionView.backgroundColor = [UIColor greenColor];
 }
@@ -43,4 +47,14 @@ - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cell
     return cell;
 }
 
+- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
+    UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:PBDCollectionElementKindSectionHeader
+                                                                        withReuseIdentifier:@"Header"
+                                                                               forIndexPath:indexPath];
+
+    view.backgroundColor = [UIColor yellowColor];
+
+    return view;
+}
+
 @end

CarouselCollectionViewLayout/Classes/Lib/Helpers/PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h → CarouselCollectionViewLayout/Classes/Lib/Internal/PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h

@@ -2,7 +2,9 @@
 * Copyright (c) 2016 Pawel Dudek. All rights reserved.
 */
 #import <Foundation/Foundation.h>
-#import "PBDCarouselCollectionViewLayout.h"
+#import "PBDCarouselCollectionViewLayoutPropertiesCache.h"
+
+@class PBDCarouselCollectionViewLayout;
 
 @interface PBDCarouselCollectionViewLayoutHorizontalPropertiesCache : NSObject <PBDCarouselCollectionViewLayoutPropertiesCache>
 

CarouselCollectionViewLayout/Classes/Lib/Helpers/PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m → CarouselCollectionViewLayout/Classes/Lib/Internal/PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.m

@@ -2,6 +2,7 @@
  * Copyright (c) 2016 Pawel Dudek. All rights reserved.
  */
 #import "PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h"
+#import "PBDCarouselCollectionViewLayout.h"
 
 
 @interface PBDCarouselCollectionViewLayoutHorizontalPropertiesCache ()
@@ -54,11 +55,18 @@ - (void)calculateLayoutProperties {
     self.cellYPosition = CGRectGetMidY(self.contentRect) - collectionView.contentInset.top;
 }
 
-#pragma mark -
+#pragma mark - Center Calculation
 
 - (CGPoint)centerForItemAtIndexPath:(NSIndexPath *)indexPath {
     CGFloat x = self.contentStart + indexPath.row * (self.layout.itemSize.width + self.layout.interItemSpace) + self.layout.itemSize.width / 2;
     return CGPointMake(x, self.cellYPosition);
 }
 
+- (CGPoint)centerForHeaderViewAtIndexPath:(NSIndexPath *)indexPath {
+    NSIndexPath *firstSectionItem = [NSIndexPath indexPathForItem:0 inSection:indexPath.section];
+    CGPoint firstItemCenter = [self centerForItemAtIndexPath:firstSectionItem];
+    firstItemCenter.x -= self.layout.itemSize.width / 2.0f + self.layout.interItemSpace + self.layout.headerSize.width / 2.0f;
+    return CGPointMake(firstItemCenter.x, self.cellYPosition);
+}
+
 @end

CarouselCollectionViewLayout/Classes/Lib/Internal/PBDCarouselCollectionViewLayoutPropertiesCache.h

@@ -0,0 +1,24 @@
+/*
+* Copyright (c) 2016 dudek. All rights reserved.
+*/
+#import <Foundation/Foundation.h>
+
+@protocol PBDCarouselCollectionViewLayoutPropertiesCache <NSObject>
+
+/*
+ * Content rect, considering content inset of collection view.
+ */
+@property(nonatomic, readonly) CGRect contentRect;
+
+/*
+ * Point on x axis that defines where actual content starts, considering size and content inset of collection view
+ */
+@property(nonatomic, readonly) CGFloat contentStart;
+
+#pragma mark - Obtaining Item Position
+
+- (CGPoint)centerForItemAtIndexPath:(NSIndexPath *)indexPath;
+
+- (CGPoint)centerForHeaderViewAtIndexPath:(NSIndexPath *)path;
+
+@end

CarouselCollectionViewLayout/Classes/Lib/PBDCarouselCollectionViewLayout.h

@@ -5,30 +5,20 @@
 
 #import <Foundation/Foundation.h>
 
-@protocol PBDCarouselCollectionViewLayoutPropertiesCache <NSObject>
-
-/*
- * Content rect, considering content inset of collection view.
- */
-@property(nonatomic, readonly) CGRect contentRect;
-
-/*
- * Point on x axis that defines where actual content starts, considering size and content inset of collection view
- */
-@property(nonatomic, readonly) CGFloat contentStart;
-
-#pragma mark - Obtaining Item Position
-
-- (CGPoint)centerForItemAtIndexPath:(NSIndexPath *)indexPath;
-
-@end
+extern NSString *PBDCollectionElementKindSectionHeader;
 
 @interface PBDCarouselCollectionViewLayout : UICollectionViewLayout
 
 @property(nonatomic) CGSize itemSize;
 
 @property(nonatomic) CGFloat interItemSpace;
-
-@property(nonatomic) CGSize headerFooterSize;
+/*
+ * Settings this to non-nil value will enable collection header view. Header view is laid out before first item in collection view.
+ * It does not participate in centering, aka you cannot center collection view on it.
+ *
+ * Defaults to CGSizeZero;
+ *
+ */
+@property(nonatomic) CGSize headerSize;
 
 @end

CarouselCollectionViewLayout/Classes/Lib/PBDCarouselCollectionViewLayout.m

@@ -4,8 +4,11 @@
 
 
 #import "PBDCarouselCollectionViewLayout.h"
+#import "PBDCarouselCollectionViewLayoutPropertiesCache.h"
 #import "PBDCarouselCollectionViewLayoutHorizontalPropertiesCache.h"
 
+NSString *PBDCollectionElementKindSectionHeader = @"PBDCollectionElementKindSectionHeader";
+
 @interface PBDCarouselCollectionViewLayout ()
 
 @property(nonatomic, strong) NSIndexPath *indexPathForCenteredItem;
@@ -54,6 +57,13 @@ - (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
         [layoutAttributes addObject:[self layoutAttributesForItemAtIndexPath:indexPath]];
     }
 
+    UICollectionViewLayoutAttributes *headerLayoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:PBDCollectionElementKindSectionHeader
+                                                                                                    atIndexPath:[NSIndexPath indexPathForItem:0
+                                                                                                                                    inSection:0]];
+    if (headerLayoutAttributes) {
+        [layoutAttributes addObject:headerLayoutAttributes];
+    }
+
     return layoutAttributes;
 }
 
@@ -69,13 +79,25 @@ - (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSInde
     return attributes;
 }
 
+- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath {
+    UICollectionViewLayoutAttributes *attributes;
+    if ([elementKind isEqualToString:PBDCollectionElementKindSectionHeader] && !CGSizeEqualToSize(self.headerSize, CGSizeZero)) {
+        attributes = [[[self class] layoutAttributesClass] layoutAttributesForSupplementaryViewOfKind:elementKind
+                                                                                        withIndexPath:indexPath];
+        attributes.size = self.headerSize;
+        attributes.center = [self.propertiesCache centerForHeaderViewAtIndexPath:indexPath];
+    }
+
+    return attributes;
+}
+
 #pragma mark - Target Content Offset
 
 - (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity {
     CGPoint targetContentOffset = proposedContentOffset;
     UICollectionViewLayoutAttributes *layoutAttributesForItemToCenterOn = [self layoutAttributesForUserFingerMovingWithVelocity:velocity
                                                                                                           proposedContentOffset:proposedContentOffset];
-
+    
     if (layoutAttributesForItemToCenterOn) {
         targetContentOffset.x = layoutAttributesForItemToCenterOn.center.x - self.collectionView.bounds.size.width / 2;
         targetContentOffset.y = 0;
@@ -103,7 +125,9 @@ - (UICollectionViewLayoutAttributes *)layoutAttributesForUserFingerMovingWithVel
     UICollectionViewLayoutAttributes *layoutAttributesForItemToCenterOn = nil;
     CGRect nextVisibleBounds = [self collectionView].bounds;
     nextVisibleBounds.origin = offset;
-    NSArray *layoutAttributesInRect = [self layoutAttributesForElementsInRect:nextVisibleBounds];
+
+    NSPredicate *itemsPredicate = [NSPredicate predicateWithFormat:@"representedElementCategory == %d", UICollectionElementCategoryCell];
+    NSArray *layoutAttributesInRect = [[self layoutAttributesForElementsInRect:nextVisibleBounds] filteredArrayUsingPredicate:itemsPredicate];
 
     if (velocity.x > 0.0f) {
         layoutAttributesForItemToCenterOn = [layoutAttributesInRect lastObject];
@@ -145,4 +169,11 @@ - (void)setItemSize:(CGSize)itemSize {
     }
 }
 
+- (void)setHeaderSize:(CGSize)headerSize {
+    if (!CGSizeEqualToSize(_headerSize, headerSize)) {
+        _headerSize = headerSize;
+        [self invalidateLayout];
+    }
+}
+
 @end