Minor changes in the library.

DraggableCollectionView/Helpers/LSCollectionViewHelper.m

@@ -30,7 +30,7 @@ typedef NS_ENUM(NSInteger, _ScrollingDirection) {
 @interface LSCollectionViewHelper ()
 {
     NSIndexPath *lastIndexPath;
-    UIImageView *mockCell;
+    UIView *mockCell;
     CGPoint mockCenter;
     CGPoint fingerTranslation;
     CADisplayLink *timer;
@@ -209,6 +209,29 @@ - (NSIndexPath *)indexPathForItemClosestToPoint:(CGPoint)point
     return indexPath;
 }
 
+- (NSIndexPath *)indexPathForItemAtPoint:(CGPoint)point
+{
+    NSArray *layoutAttrsInRect;
+    NSIndexPath *indexPath;
+    NSIndexPath *toIndexPath = self.layoutHelper.toIndexPath;
+
+    // We need original positions of cells
+    self.layoutHelper.toIndexPath = nil;
+    layoutAttrsInRect = [self.collectionView.collectionViewLayout layoutAttributesForElementsInRect:self.collectionView.bounds];
+    self.layoutHelper.toIndexPath = toIndexPath;
+
+    // What cell are we closest to?
+    for (UICollectionViewLayoutAttributes *layoutAttr in layoutAttrsInRect)
+    {
+        if (CGRectContainsPoint(layoutAttr.frame, point))
+        {
+            indexPath = layoutAttr.indexPath;
+        }
+    }
+
+    return indexPath;
+}
+
 - (void)handleLongPressGesture:(UILongPressGestureRecognizer *)sender
 {
     if (sender.state == UIGestureRecognizerStateChanged) {
@@ -218,7 +241,7 @@ - (void)handleLongPressGesture:(UILongPressGestureRecognizer *)sender
         return;
     }
 
-    NSIndexPath *indexPath = [self indexPathForItemClosestToPoint:[sender locationInView:self.collectionView]];
+    NSIndexPath *indexPath = [self indexPathForItemAtPoint:[sender locationInView:self.collectionView]];
 
     switch (sender.state) {
         case UIGestureRecognizerStateBegan: {
@@ -234,16 +257,42 @@ - (void)handleLongPressGesture:(UILongPressGestureRecognizer *)sender
             UICollectionViewCell *cell = [self.collectionView cellForItemAtIndexPath:indexPath];
             cell.highlighted = NO;
             [mockCell removeFromSuperview];
-            mockCell = [[UIImageView alloc] initWithFrame:cell.frame];
-            mockCell.image = [self imageFromCell:cell];
+            if([self.collectionView.dataSource respondsToSelector:@selector(collectionView:viewForDraggingAtIndexPath:)])
+            {
+                mockCell = [(id<UICollectionViewDataSource_Draggable>)self.collectionView.dataSource
+                            collectionView:self.collectionView viewForDraggingAtIndexPath:indexPath];
+                mockCell.center = cell.center;
+            }
+            else
+            {
+                mockCell = [[UIImageView alloc] initWithFrame:cell.frame];
+                ((UIImageView *)mockCell).image = [self imageFromCell:cell];
+            }
             mockCenter = mockCell.center;
-            [self.collectionView addSubview:mockCell];
-            [UIView
-             animateWithDuration:0.3
-             animations:^{
-                 mockCell.transform = CGAffineTransformMakeScale(1.1f, 1.1f);
-             }
-             completion:nil];
+            // Adding the mock cell to the root window so that if the collection view is not full screen,
+            // it is not clipped by the collection view when dragging.
+            [[self rootView] addSubview:mockCell];
+
+            mockCell.center = [self convertPointToRootView:mockCenter];
+
+            if([mockCell isKindOfClass:[UIImageView class]])
+            {
+                [UIView
+                 animateWithDuration:0.3
+                 animations:^{
+                     mockCell.transform = CGAffineTransformMakeScale(1.1f, 1.1f);
+                 }
+                 completion:nil];
+            }
+            else
+            {
+                mockCell.transform = CGAffineTransformMakeScale((cell.bounds.size.width/mockCell.bounds.size.width),
+                                                                (cell.bounds.size.height/mockCell.bounds.size.height));
+                [UIView animateWithDuration:0.3f
+                                 animations:^{
+                    mockCell.transform = CGAffineTransformIdentity;
+                }];
+            }
 
             // Start warping
             lastIndexPath = indexPath;
@@ -274,8 +323,19 @@ - (void)handleLongPressGesture:(UILongPressGestureRecognizer *)sender
             [UIView
              animateWithDuration:0.3
              animations:^{
-                 mockCell.center = layoutAttributes.center;
-                 mockCell.transform = CGAffineTransformMakeScale(1.f, 1.f);
+                 mockCell.center = [self convertPointToRootView:layoutAttributes.center];
+
+                 CGAffineTransform transform = CGAffineTransformIdentity;
+                 if([mockCell isKindOfClass:[UIImageView class]])
+                 {
+                     transform = CGAffineTransformMakeScale(1.f, 1.f);
+                 }
+                 else
+                 {
+                     transform = CGAffineTransformMakeScale((layoutAttributes.frame.size.width/mockCell.bounds.size.width),
+                                                            (layoutAttributes.frame.size.height/mockCell.bounds.size.height));
+                 }
+                 mockCell.transform = transform;
              }
              completion:^(BOOL finished) {
                  [mockCell removeFromSuperview];
@@ -317,17 +377,18 @@ - (void)handlePanGesture:(UIPanGestureRecognizer *)sender
     if(sender.state == UIGestureRecognizerStateChanged) {
         // Move mock to match finger
         fingerTranslation = [sender translationInView:self.collectionView];
-        mockCell.center = _CGPointAdd(mockCenter, fingerTranslation);
+        CGPoint center = _CGPointAdd(mockCenter, fingerTranslation);
+        mockCell.center = [self convertPointToRootView:center];
 
         // Scroll when necessary
         if (canScroll) {
             UICollectionViewFlowLayout *scrollLayout = (UICollectionViewFlowLayout*)self.collectionView.collectionViewLayout;
             if([scrollLayout scrollDirection] == UICollectionViewScrollDirectionVertical) {
-                if (mockCell.center.y < (CGRectGetMinY(self.collectionView.bounds) + self.scrollingEdgeInsets.top)) {
+                if (center.y < (CGRectGetMinY(self.collectionView.bounds) + self.scrollingEdgeInsets.top)) {
                     [self setupScrollTimerInDirection:_ScrollingDirectionUp];
                 }
                 else {
-                    if (mockCell.center.y > (CGRectGetMaxY(self.collectionView.bounds) - self.scrollingEdgeInsets.bottom)) {
+                    if (center.y > (CGRectGetMaxY(self.collectionView.bounds) - self.scrollingEdgeInsets.bottom)) {
                         [self setupScrollTimerInDirection:_ScrollingDirectionDown];
                     }
                     else {
@@ -336,10 +397,10 @@ - (void)handlePanGesture:(UIPanGestureRecognizer *)sender
                 }
             }
             else {
-                if (mockCell.center.x < (CGRectGetMinX(self.collectionView.bounds) + self.scrollingEdgeInsets.left)) {
+                if (center.x < (CGRectGetMinX(self.collectionView.bounds) + self.scrollingEdgeInsets.left)) {
                     [self setupScrollTimerInDirection:_ScrollingDirectionLeft];
                 } else {
-                    if (mockCell.center.x > (CGRectGetMaxX(self.collectionView.bounds) - self.scrollingEdgeInsets.right)) {
+                    if (center.x > (CGRectGetMaxX(self.collectionView.bounds) - self.scrollingEdgeInsets.right)) {
                         [self setupScrollTimerInDirection:_ScrollingDirectionRight];
                     } else {
                         [self invalidatesScrollTimer];
@@ -404,12 +465,28 @@ - (void)handleScroll:(NSTimer *)timer {
     }
 
     mockCenter  = _CGPointAdd(mockCenter, translation);
-    mockCell.center = _CGPointAdd(mockCenter, fingerTranslation);
+    CGPoint center = _CGPointAdd(mockCenter, fingerTranslation);
     self.collectionView.contentOffset = _CGPointAdd(contentOffset, translation);
 
     // Warp items while scrolling
-    NSIndexPath *indexPath = [self indexPathForItemClosestToPoint:mockCell.center];
+    NSIndexPath *indexPath = [self indexPathForItemClosestToPoint:center];
     [self warpToIndexPath:indexPath];
 }
 
+- (CGPoint)convertPointToRootView:(CGPoint)point
+{
+    return [self.collectionView convertPoint:point toView:[self rootView]];
+}
+
+- (CGPoint)convertPointFromRootView:(CGPoint)point
+{
+    return [self.collectionView convertPoint:point fromView:[self rootView]];
+}
+
+- (UIView *)rootView
+{
+    UIWindow *window = [[UIApplication sharedApplication] keyWindow];
+    return window.subviews[0];
+}
+
 @end

DraggableCollectionView/UICollectionViewDataSource_Draggable.h

@@ -18,4 +18,9 @@
 
 - (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)toIndexPath;
 
+// When dragging by default a cell copy (image) is created and tranform is applied.
+// If you think the image looks blur when transform is applied, you can provide your own view by invoking this method.
+// This method assumes that your view big enough so no transform is applied. 
+- (UIView *)collectionView:(UICollectionView *)collectionView viewForDraggingAtIndexPath:(NSIndexPath *)indexPath;
+
 @end

FlowLayoutDemo/ViewController.m

@@ -76,4 +76,17 @@ - (void)collectionView:(LSCollectionViewHelper *)collectionView moveItemAtIndexP
     [data2 insertObject:index atIndex:toIndexPath.item];
 }
 
+- (UIView *)collectionView:(UICollectionView *)collectionView viewForDraggingAtIndexPath:(NSIndexPath *)indexPath
+{
+    NSMutableArray *data = [sections objectAtIndex:indexPath.section];
+    NSString *text = [data objectAtIndex:indexPath.item];
+
+    UILabel *draggingView = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 200.0f, 200.0f)];
+    draggingView.backgroundColor = [UIColor lightGrayColor];
+    draggingView.font = [draggingView.font fontWithSize:draggingView.font.pointSize + 16.0f];
+    draggingView.textAlignment = NSTextAlignmentCenter;
+    draggingView.text = text;
+    return draggingView;
+}
+
 @end