Instance Method

collectionView:draggingSession:willBeginAtPoint:forItemsAtIndexes:

Notifies your delegate that a drag session is about to begin.

Declaration

- (void)collectionView:(NSCollectionView *)collectionView draggingSession:(NSDraggingSession *)session willBeginAtPoint:(NSPoint)screenPoint forItemsAtIndexes:(NSIndexSet *)indexes;

Parameters

collectionView

The collection view notifying your delegate object.

session

The dragging session that is about to begin.

screenPoint

The starting point (in screen coordinates) for the drag operation.

indexes

The indexes of the items being dragged.

Discussion

You can use this method to modify the dragging session or to perform other tasks related to the beginning of a drag session.

See Also

Legacy Collection View Support

- collectionView:canDragItemsAtIndexes:withEvent:

Returns a Boolean indicating whether the collection view can begin dragging the specified items.

- collectionView:pasteboardWriterForItemAtIndex:

Provides the pasteboard writer for the item at the specified index

- collectionView:writeItemsAtIndexes:toPasteboard:

Invoked after it has been determined that a drag should begin, but before the drag has been started.

Deprecated
- collectionView:namesOfPromisedFilesDroppedAtDestination:forDraggedItemsAtIndexes:

Invoked to return an array of filenames that the receiver promises to create.

Deprecated
- collectionView:draggingImageForItemsAtIndexes:withEvent:offset:

Creates and returns a drag image to represent the specified items during a drag.

- collectionView:validateDrop:proposedIndex:dropOperation:

Validates the specified location to see if it is a valid drop target.

- collectionView:acceptDrop:index:dropOperation:

Invoked when the mouse is released over a collection view that previously allowed a drop.