outlineView(_:validateDrop:proposedItem:proposedChildIndex:)

Declaration

@MainActor optional func outlineView(_ outlineView: NSOutlineView, validateDrop info: any NSDraggingInfo, proposedItem item: Any?, proposedChildIndex index: Int) -> NSDragOperation

Parameters

• outlineView:

  The outline view that sent the message.

• info:

  An object that contains more information about this dragging operation.

• item:

  The proposed parent.

• index:

  The proposed child location.

Return Value

A value that indicates which dragging operation the data source will perform.

Discussion

Based on the mouse position, the outline view will suggest a proposed drop location. The data source may “retarget” a drop if desired by calling setDropItem(_:dropChildIndex:) and returning something other than NSDragOperationNone. You may choose to retarget for various reasons (for example, for better visual feedback when inserting into a sorted position).

Implementation of this method is optional.

See Also

Instance Methods

• outlineView(_:acceptDrop:item:childIndex:)
• outlineView(_:child:ofItem:)
• outlineView(_:draggingSession:endedAt:operation:)
• outlineView(_:draggingSession:willBeginAt:forItems:)
• outlineView(_:isItemExpandable:)
• outlineView(_:itemForPersistentObject:)
• outlineView(_:namesOfPromisedFilesDroppedAtDestination:forDraggedItems:)
• outlineView(_:numberOfChildrenOfItem:)
• outlineView(_:objectValueFor:byItem:)
• outlineView(_:pasteboardWriterForItem:)
• outlineView(_:persistentObjectForItem:)
• outlineView(_:setObjectValue:for:byItem:)
• outlineView(_:sortDescriptorsDidChange:)
• outlineView(_:updateDraggingItemsForDrag:)
• outlineView(_:writeItems:to:)