dropInteraction(_:previewForDropping:withDefault:)

Declaration

optional func dropInteraction(_ interaction: UIDropInteraction, previewForDropping item: UIDragItem, withDefault defaultPreview: UITargetedDragPreview) -> UITargetedDragPreview?

Parameters

• interaction:

  The interaction that called this method.

• item:

  The drag item represented by the preview.

• defaultPreview:

  A targeted drag preview provided by the system, if this is the first call for this item; otherwise, it’s the previous value for the drag preview.

Return Value

• The default preview, which is the same behavior as not implementing this method.

• A targeted drag item preview that you create.

• The preview returned after moving to a new preview target by using the defaultPreview’s retargetedPreview(with:) method.

• nil to fade the preview that is currently displayed to the user.

Discussion

The system calls this method multiple times, once for each visible drag item. It shows the preview during the drop animation in order to visually drop the drag item into place.

If you call setNeedsDropPreviewUpdate() to tell the system to request a new drop preview, the system provides the previous value in the defaultPreview parameter.

See Also

Animating the drop

• dropInteraction(_:item:willAnimateDropWith:)
• dropInteraction(_:concludeDrop:)