collectionView(_:draggingSession:willBeginAt:forItemsAt:)

Declaration

@MainActor optional func collectionView(_ collectionView: NSCollectionView, draggingSession session: NSDraggingSession, willBeginAt screenPoint: NSPoint, forItemsAt indexPaths: Set<IndexPath>)

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.

• indexPaths:

  The index paths 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

Drag and Drop Support

• Supporting Collection View Drag and Drop Through File Promises
• collectionView(_:canDragItemsAt:with:)
• collectionView(_:pasteboardWriterForItemAt:)
• collectionView(_:writeItemsAt:to:)
• collectionView(_:namesOfPromisedFilesDroppedAtDestination:forDraggedItemsAt:)
• collectionView(_:draggingImageForItemsAt:with:offset:)
• collectionView(_:draggingSession:endedAt:dragOperation:)
• collectionView(_:updateDraggingItemsForDrag:)
• collectionView(_:validateDrop:proposedIndexPath:dropOperation:)
• collectionView(_:acceptDrop:indexPath:dropOperation:)