apple.uikit.protocol

Interface UICollectionViewDropDelegate

public interface UICollectionViewDropDelegate

Method Summary

Modifier and Type	Method and Description
default boolean	collectionViewCanHandleDropSession(UICollectionView collectionView, UIDropSession session) If NO is returned no further delegate methods will be called for this drop session.
default UIDragPreviewParameters	collectionViewDropPreviewParametersForItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath) Allows customization of the preview used for the item being dropped.
default void	collectionViewDropSessionDidEnd(UICollectionView collectionView, UIDropSession session) Called when the drop session completed, regardless of outcome.
default void	collectionViewDropSessionDidEnter(UICollectionView collectionView, UIDropSession session) Called when the drop session begins tracking in the collection view's coordinate space.
default void	collectionViewDropSessionDidExit(UICollectionView collectionView, UIDropSession session) Called when the drop session is no longer being tracked inside the collection view's coordinate space.
default UICollectionViewDropProposal	collectionViewDropSessionDidUpdateWithDestinationIndexPath(UICollectionView collectionView, UIDropSession session, NSIndexPath destinationIndexPath) Called frequently while the drop session being tracked inside the collection view's coordinate space.
void	collectionViewPerformDropWithCoordinator(UICollectionView collectionView, UICollectionViewDropCoordinator coordinator) Called when the user initiates the drop.

Method Detail

collectionViewCanHandleDropSession

default boolean collectionViewCanHandleDropSession(UICollectionView collectionView,
                                                   UIDropSession session)

If NO is returned no further delegate methods will be called for this drop session. If not implemented, a default value of YES is assumed.

collectionViewDropPreviewParametersForItemAtIndexPath

default UIDragPreviewParameters collectionViewDropPreviewParametersForItemAtIndexPath(UICollectionView collectionView,
                                                                                      NSIndexPath indexPath)

Allows customization of the preview used for the item being dropped. If not implemented or if nil is returned, the entire cell will be used for the preview.

This will be called as needed when animating drops via -[UICollectionViewDropCoordinator dropItem:toItemAtIndexPath:] (to customize placeholder drops, please see UICollectionViewDropPlaceholder.previewParametersProvider)

collectionViewDropSessionDidEnd

default void collectionViewDropSessionDidEnd(UICollectionView collectionView,
                                             UIDropSession session)

Called when the drop session completed, regardless of outcome. Useful for performing any cleanup.

collectionViewDropSessionDidEnter

default void collectionViewDropSessionDidEnter(UICollectionView collectionView,
                                               UIDropSession session)

Called when the drop session begins tracking in the collection view's coordinate space.

collectionViewDropSessionDidExit

default void collectionViewDropSessionDidExit(UICollectionView collectionView,
                                              UIDropSession session)

Called when the drop session is no longer being tracked inside the collection view's coordinate space.

collectionViewDropSessionDidUpdateWithDestinationIndexPath

default UICollectionViewDropProposal collectionViewDropSessionDidUpdateWithDestinationIndexPath(UICollectionView collectionView,
                                                                                                UIDropSession session,
                                                                                                NSIndexPath destinationIndexPath)

Called frequently while the drop session being tracked inside the collection view's coordinate space. When the drop is at the end of a section, the destination index path passed will be for a item that does not yet exist (equal to the number of items in that section), where an inserted item would append to the end of the section. The destination index path may be nil in some circumstances (e.g. when dragging over empty space where there are no cells). Note that in some cases your proposal may not be allowed and the system will enforce a different proposal. You may perform your own hit testing via -[UIDropSession locationInView]

collectionViewPerformDropWithCoordinator

void collectionViewPerformDropWithCoordinator(UICollectionView collectionView,
                                              UICollectionViewDropCoordinator coordinator)

Called when the user initiates the drop. Use the dropCoordinator to specify how you wish to animate the dropSession's items into their final position as well as update the collection view's data source with data retrieved from the dropped items. If the supplied method does nothing, default drop animations will be supplied and the collection view will revert back to its initial pre-drop session state.