Accepting drag operations in a subclass of NSCollectionView

Question

I have subclassed NSCollectionView and I am trying to get dragged files from Finder. I get draggingEntered:and return the appropriate value, but I never get prepareForDragOperation:(and not one of the methods after that in the process). Is there something obvious I'm missing here?

the code:

- (void)awakeFromNib
{
    [self registerForDraggedTypes:[NSArray arrayWithObjects:NSFilenamesPboardType, nil]];
}

- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
{
    NSLog(@"entered"); //Happens
    NSPasteboard *pboard;
    NSDragOperation sourceDragMask;

    sourceDragMask = [sender draggingSourceOperationMask];
    pboard = [sender draggingPasteboard];

    if ([[pboard types] containsObject:NSFilenamesPboardType])
    {
        NSLog(@"copy"); //Happens
        return NSDragOperationCopy;
    }

    return NSDragOperationNone;
}

- (BOOL)prepareForDragOperation:(id <NSDraggingInfo>)sender
{
    NSLog(@"prepare"); //Never happens
    return YES;
}

Answer 1

This is pretty late, but I found the problem:

NSCollectionView silently provides an incompatible implementation:

-(NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender

... Apple . draggingEntered, , :

-(NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender
{
    return [self draggingEntered:sender];
}

( SO, , "" , ... (, Apple!). , - -point CollectionView?).

UPDATE: , NSCollectionView. - Xcode4 , , . / .

( , , , -, , )

Answer 2

, NSCollectionViewDelegate Protocol

- (NSDragOperation)collectionView:(NSCollectionView *)collectionView validateDrop:(id <NSDraggingInfo> )draggingInfo proposedIndex:(NSInteger *)proposedDropIndex dropOperation:(NSCollectionViewDropOperation *)proposedDropOperation;
- (BOOL)collectionView:(NSCollectionView *)collectionView acceptDrop:(id <NSDraggingInfo> )draggingInfo index:(NSInteger)index dropOperation:(NSCollectionViewDropOperation)dropOperation;

- (BOOL)collectionView:(NSCollectionView *)collectionView canDragItemsAtIndexes:(NSIndexSet *)indexes withEvent:(NSEvent *)event;
- (NSImage *)collectionView:(NSCollectionView *)collectionView draggingImageForItemsAtIndexes:(NSIndexSet *)indexes withEvent:(NSEvent *)event offset:(NSPointPointer)dragImageOffset;
- (NSArray *)collectionView:(NSCollectionView *)collectionView namesOfPromisedFilesDroppedAtDestination:(NSURL *)dropURL forDraggedItemsAtIndexes:(NSIndexSet *)indexes;
- (BOOL)collectionView:(NSCollectionView *)collectionView writeItemsAtIndexes:(NSIndexSet *)indexes toPasteboard:(NSPasteboard *)pasteboard;

.

Answer 3

I went through this a while ago. It seemed uninteresting to me, but the only way to make it work is to create a linked scroll view as the target.