Delegate integration for custom scroll events

LXRCVFL Example using Storyboard/LXRCVFL Example using Storyboard.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		927A97F41736CA0E00539F5E /* QuartzCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 927A97F31736CA0E00539F5E /* QuartzCore.framework */; };
 		AB0E97C7161B4BEC005498A0 /* UIKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = AB0E97C6161B4BEC005498A0 /* UIKit.framework */; };
 		AB0E97C9161B4BEC005498A0 /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = AB0E97C8161B4BEC005498A0 /* Foundation.framework */; };
 		AB0E97CB161B4BEC005498A0 /* CoreGraphics.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = AB0E97CA161B4BEC005498A0 /* CoreGraphics.framework */; };
@@ -25,6 +26,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		927A97F31736CA0E00539F5E /* QuartzCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = QuartzCore.framework; path = System/Library/Frameworks/QuartzCore.framework; sourceTree = SDKROOT; };
 		AB0E97C2161B4BEC005498A0 /* LXRCVFL Example using Storyboard.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = "LXRCVFL Example using Storyboard.app"; sourceTree = BUILT_PRODUCTS_DIR; };
 		AB0E97C6161B4BEC005498A0 /* UIKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = UIKit.framework; path = System/Library/Frameworks/UIKit.framework; sourceTree = SDKROOT; };
 		AB0E97C8161B4BEC005498A0 /* Foundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Foundation.framework; path = System/Library/Frameworks/Foundation.framework; sourceTree = SDKROOT; };
@@ -55,6 +57,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				927A97F41736CA0E00539F5E /* QuartzCore.framework in Frameworks */,
 				AB0E97C7161B4BEC005498A0 /* UIKit.framework in Frameworks */,
 				AB0E97C9161B4BEC005498A0 /* Foundation.framework in Frameworks */,
 				AB0E97CB161B4BEC005498A0 /* CoreGraphics.framework in Frameworks */,
@@ -86,6 +89,7 @@
 		AB0E97C5161B4BEC005498A0 /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
+				927A97F31736CA0E00539F5E /* QuartzCore.framework */,
 				AB0E97C6161B4BEC005498A0 /* UIKit.framework */,
 				AB0E97C8161B4BEC005498A0 /* Foundation.framework */,
 				AB0E97CA161B4BEC005498A0 /* CoreGraphics.framework */,

LXRCVFL Example using Storyboard/LXRCVFL Example using Storyboard/LXCollectionViewController.h

@@ -9,7 +9,7 @@
 #import <UIKit/UIKit.h>
 #import "LXReorderableCollectionViewFlowLayout.h"
 
-@interface LXCollectionViewController : UICollectionViewController <LXReorderableCollectionViewDatasource, LXReorderableCollectionViewDelegateFlowLayout>
+@interface LXCollectionViewController : UICollectionViewController <LXReorderableCollectionViewDataSource, LXReorderableCollectionViewDelegateFlowLayout>
 
 @property (strong, nonatomic) NSMutableArray *deck;
 

LXRCVFL Example using Storyboard/LXRCVFL Example using Storyboard/LXCollectionViewController.m

@@ -78,7 +78,7 @@ - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cell
     return playingCardCell;
 }
 
-#pragma mark - LXReorderableCollectionViewDatasource methods
+#pragma mark - LXReorderableCollectionViewDataSource methods
 
 - (void)collectionView:(UICollectionView *)collectionView itemAtIndexPath:(NSIndexPath *)fromIndexPath willMoveToIndexPath:(NSIndexPath *)toIndexPath {
     PlayingCard *playingCard = [self.deck objectAtIndex:fromIndexPath.item];

LXReorderableCollectionViewFlowLayout/LXReorderableCollectionViewFlowLayout.h

@@ -11,19 +11,20 @@
 
 @property (assign, nonatomic) CGFloat scrollingSpeed;
 @property (assign, nonatomic) UIEdgeInsets scrollingTriggerEdgeInsets;
-@property (weak, nonatomic, readonly) UILongPressGestureRecognizer *longPressGestureRecognizer;
-@property (weak, nonatomic, readonly) UIPanGestureRecognizer *panGestureRecognizer;
+@property (strong, nonatomic, readonly) UILongPressGestureRecognizer *longPressGestureRecognizer;
+@property (strong, nonatomic, readonly) UIPanGestureRecognizer *panGestureRecognizer;
 
 - (void)setUpGestureRecognizersOnCollectionView __attribute__((deprecated("Calls to setUpGestureRecognizersOnCollectionView method are not longer needed as setup are done automatically through KVO.")));
 
 @end
 
-@protocol LXReorderableCollectionViewDatasource <UICollectionViewDataSource>
-
-- (void)collectionView:(UICollectionView *)collectionView itemAtIndexPath:(NSIndexPath *)fromIndexPath willMoveToIndexPath:(NSIndexPath *)toIndexPath;
+@protocol LXReorderableCollectionViewDataSource <UICollectionViewDataSource>
 
 @optional
 
+- (void)collectionView:(UICollectionView *)collectionView itemAtIndexPath:(NSIndexPath *)fromIndexPath willMoveToIndexPath:(NSIndexPath *)toIndexPath;
+- (void)collectionView:(UICollectionView *)collectionView itemAtIndexPath:(NSIndexPath *)fromIndexPath didMoveToIndexPath:(NSIndexPath *)toIndexPath;
+
 - (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath;
 - (BOOL)collectionView:(UICollectionView *)collectionView itemAtIndexPath:(NSIndexPath *)fromIndexPath canMoveToIndexPath:(NSIndexPath *)toIndexPath;
 
@@ -37,4 +38,7 @@
 - (void)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout willEndDraggingItemAtIndexPath:(NSIndexPath *)indexPath;
 - (void)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout didEndDraggingItemAtIndexPath:(NSIndexPath *)indexPath;
 
+- (void)collectionViewScrollToNextPage:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout;
+- (void)collectionViewScrollToPreviousPage:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout;
+
 @end

LXReorderableCollectionViewFlowLayout/LXReorderableCollectionViewFlowLayout.m

@@ -7,6 +7,7 @@
 
 #import "LXReorderableCollectionViewFlowLayout.h"
 #import <QuartzCore/QuartzCore.h>
+#import <objc/runtime.h>
 
 #define LX_FRAMES_PER_SECOND 60.0
 
@@ -73,6 +74,20 @@ - (CGPoint)LX_contentOffsetForPageIndex:(NSInteger)pageIndex {
 
 @end
 
+@interface CADisplayLink (LX_userInfo)
+@property (nonatomic, copy) NSDictionary *LX_userInfo;
+@end
+
+@implementation CADisplayLink (LX_userInfo)
+- (void) setLX_userInfo:(NSDictionary *) LX_userInfo {
+    objc_setAssociatedObject(self, "LX_userInfo", LX_userInfo, OBJC_ASSOCIATION_COPY);
+}
+
+- (NSDictionary *) LX_userInfo {
+    return objc_getAssociatedObject(self, "LX_userInfo");
+}
+@end
+
 @interface UICollectionViewCell (LXReorderableCollectionViewFlowLayout)
 
 - (UIImage *)LX_rasterizedImage;
@@ -97,9 +112,9 @@ @interface LXReorderableCollectionViewFlowLayout ()
 @property (strong, nonatomic) UIView *currentView;
 @property (assign, nonatomic) CGPoint currentViewCenter;
 @property (assign, nonatomic) CGPoint panTranslationInCollectionView;
-@property (strong, nonatomic) NSTimer *scrollingTimer;
+@property (strong, nonatomic) CADisplayLink *displayLink;
 
-@property (assign, nonatomic, readonly) id<LXReorderableCollectionViewDatasource> dataSource;
+@property (assign, nonatomic, readonly) id<LXReorderableCollectionViewDataSource> dataSource;
 @property (assign, nonatomic, readonly) id<LXReorderableCollectionViewDelegateFlowLayout> delegate;
 
 @end
@@ -114,25 +129,24 @@ - (void)setDefaults {
 }
 
 - (void)setupCollectionView {
-    UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self
-                                                                                                             action:@selector(handleLongPressGesture:)];
-    longPressGestureRecognizer.delegate = self;
-    [self.collectionView addGestureRecognizer:longPressGestureRecognizer];
+    _longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self
+                                                                                action:@selector(handleLongPressGesture:)];
+    _longPressGestureRecognizer.delegate = self;
 
     // Links the default long press gesture recognizer to the custom long press gesture recognizer we are creating now
     // by enforcing failure dependency so that they doesn't clash.
     for (UIGestureRecognizer *gestureRecognizer in self.collectionView.gestureRecognizers) {
         if ([gestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {
-            [gestureRecognizer requireGestureRecognizerToFail:longPressGestureRecognizer];
+            [gestureRecognizer requireGestureRecognizerToFail:_longPressGestureRecognizer];
         }
     }
-    _longPressGestureRecognizer = longPressGestureRecognizer;
 
-    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
-                                                                                           action:@selector(handlePanGesture:)];
-    panGestureRecognizer.delegate = self;
-    [self.collectionView addGestureRecognizer:panGestureRecognizer];
-    _panGestureRecognizer = panGestureRecognizer;
+    [self.collectionView addGestureRecognizer:_longPressGestureRecognizer];
+
+    _panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
+                                                                    action:@selector(handlePanGesture:)];
+    _panGestureRecognizer.delegate = self;
+    [self.collectionView addGestureRecognizer:_panGestureRecognizer];
 }
 
 - (id)init {
@@ -164,8 +178,8 @@ - (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttribut
     }
 }
 
-- (id<LXReorderableCollectionViewDatasource>)dataSource {
-    return (id<LXReorderableCollectionViewDatasource>)self.collectionView.dataSource;
+- (id<LXReorderableCollectionViewDataSource>)dataSource {
+    return (id<LXReorderableCollectionViewDataSource>)self.collectionView.dataSource;
 }
 
 - (id<LXReorderableCollectionViewDelegateFlowLayout>)delegate {
@@ -188,23 +202,30 @@ - (void)invalidateLayoutIfNecessary {
 
     self.selectedItemIndexPath = newIndexPath;
 
-    [self.dataSource collectionView:self.collectionView itemAtIndexPath:previousIndexPath willMoveToIndexPath:newIndexPath];
-
+    if ([self.dataSource respondsToSelector:@selector(collectionView:itemAtIndexPath:willMoveToIndexPath:)]) {
+        [self.dataSource collectionView:self.collectionView itemAtIndexPath:previousIndexPath willMoveToIndexPath:newIndexPath];
+    }
+
     __weak typeof(self) weakSelf = self;
     [self.collectionView performBatchUpdates:^{
         __strong typeof(self) strongSelf = weakSelf;
         if (strongSelf) {
             [strongSelf.collectionView deleteItemsAtIndexPaths:@[ previousIndexPath ]];
             [strongSelf.collectionView insertItemsAtIndexPaths:@[ newIndexPath ]];
         }
-    } completion:nil];
+    } completion:^(BOOL finished) {
+        __strong typeof(self) strongSelf = weakSelf;
+        if ([strongSelf.dataSource respondsToSelector:@selector(collectionView:itemAtIndexPath:didMoveToIndexPath:)]) {
+            [strongSelf.dataSource collectionView:strongSelf.collectionView itemAtIndexPath:previousIndexPath didMoveToIndexPath:newIndexPath];
+        }
+    }];
 }
 
 - (void)invalidatesScrollTimer {
-    if (self.scrollingTimer.isValid) {
-        [self.scrollingTimer invalidate];
+    if (!self.displayLink.paused) {
+        [self.displayLink invalidate];
     }
-    self.scrollingTimer = nil;
+    self.displayLink = nil;
 }
 
 - (void)scrollIfNecessary {
@@ -271,11 +292,17 @@ - (void)scrollWithDirection:(LXScrollingDirection)direction {
         switch(direction) {
             case LXScrollingDirectionUp:
             case LXScrollingDirectionLeft: {
-                [self scrollToPreviousPage];
+                if([self.delegate respondsToSelector:@selector(collectionViewScrollToPreviousPage:layout:)])
+                    [self.delegate collectionViewScrollToPreviousPage:self.collectionView layout:self];
+                else
+                    [self scrollToPreviousPage];
             } break;
             case LXScrollingDirectionDown:
             case LXScrollingDirectionRight: {
-                [self scrollToNextPage];
+                if([self.delegate respondsToSelector:@selector(collectionViewScrollToNextPage:layout:)])
+                    [self.delegate collectionViewScrollToNextPage:self.collectionView layout:self];
+                else
+                    [self scrollToNextPage];
             } break;
             default: {
                 // Do nothing...
@@ -287,28 +314,27 @@ - (void)scrollWithDirection:(LXScrollingDirection)direction {
 }
 
 - (void)setupScrollTimerInDirection:(LXScrollingDirection)direction {
-    if (self.scrollingTimer.isValid) {
-        LXScrollingDirection oldDirection = [self.scrollingTimer.userInfo[kLXScrollingDirectionKey] integerValue];
-        
+    if (!self.displayLink.paused) {
+        LXScrollingDirection oldDirection = [self.displayLink.LX_userInfo[kLXScrollingDirectionKey] integerValue];
+
         if (direction == oldDirection) {
             return;
         }
     }
 
     [self invalidatesScrollTimer];
-
-    self.scrollingTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 / LX_FRAMES_PER_SECOND
-                                                           target:self
-                                                         selector:@selector(handleScroll:)
-                                                         userInfo:@{ kLXScrollingDirectionKey : @(direction) }
-                                                          repeats:YES];
+
+    self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(handleScroll:)];
+    self.displayLink.LX_userInfo = @{ kLXScrollingDirectionKey : @(direction) };
+
+    [self.displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
 }
 
 #pragma mark - Target/Action methods
 
 // Tight loop, allocate memory sparely, even if they are stack allocation.
-- (void)handleScroll:(NSTimer *)timer {
-    LXScrollingDirection direction = (LXScrollingDirection)[timer.userInfo[kLXScrollingDirectionKey] integerValue];
+- (void)handleScroll:(CADisplayLink *)displayLink {
+    LXScrollingDirection direction = (LXScrollingDirection)[displayLink.LX_userInfo[kLXScrollingDirectionKey] integerValue];
     if (direction == LXScrollingDirectionUnknown) {
         return;
     }

README.md

@@ -62,7 +62,12 @@ Credits
 - Refactored by [Luke Scott](https://github.com/lukescott), with some help from [mulle-nat's fork](https://github.com/mulle-nat/LXReorderableCollectionViewFlowLayout).
 - Playing cards in the demo are downloaded from [http://www.jfitz.com/cards/](http://www.jfitz.com/cards/).
 
+Alternatives
+============
+
+- [DraggableCollectionView](https://github.com/lukescott/DraggableCollectionView) by [Luke Scott](https://github.com/lukescott).
+
 License
 =======
 
-LXReorderableCollectionViewFlowLayout is available under the MIT license.
+LXReorderableCollectionViewFlowLayout is available under [the MIT license](LICENSE).