apple.uikit.protocol

Interface UIDropInteractionDelegate

public interface UIDropInteractionDelegate

Method Summary

Modifier and Type	Method and Description
default boolean	dropInteractionCanHandleSession(UIDropInteraction interaction, UIDropSession session) Return whether the delegate is interested in the given session.
default void	dropInteractionConcludeDrop(UIDropInteraction interaction, UIDropSession session) Called when the user has dropped onto this interaction's view, after `-dropInteraction:performDrop:` has been called, and all resulting drop animations have completed.
default void	dropInteractionItemWillAnimateDropWithAnimator(UIDropInteraction interaction, UIDragItem item, UIDragAnimating animator) Called when the drop animation is about to start, once for each item, whether it is visible or not.
default void	dropInteractionPerformDrop(UIDropInteraction interaction, UIDropSession session) Called when the user drops onto this interaction's view.
default UITargetedDragPreview	dropInteractionPreviewForDroppingItemWithDefault(UIDropInteraction interaction, UIDragItem item, UITargetedDragPreview defaultPreview) Called when the drop happens, after `-dropInteraction:performDrop:`, once for each visible item.
default void	dropInteractionSessionDidEnd(UIDropInteraction interaction, UIDropSession session) When the drag session ends, for any reason, this method will be called for *every* interaction that ever received `-dropInteraction:sessionDidEnter:`, `-dropInteraction:sessionDidUpdate:`, or `-dropInteraction:sessionDidExit:`.
default void	dropInteractionSessionDidEnter(UIDropInteraction interaction, UIDropSession session) Called when a drag enters the view.
default void	dropInteractionSessionDidExit(UIDropInteraction interaction, UIDropSession session) Called when the drag has exited the interaction's view.
default UIDropProposal	dropInteractionSessionDidUpdate(UIDropInteraction interaction, UIDropSession session) Called when the drag enters the interaction's view, or when when the drag moves while inside the view, or if items are added to the drag while inside the view.

Method Detail

dropInteractionCanHandleSession

default boolean dropInteractionCanHandleSession(UIDropInteraction interaction,
                                                UIDropSession session)

Return whether the delegate is interested in the given session. If this method is not implemented, or if it returns true, then the other delegate methods will be called, starting with `-dropInteraction:sessionDidEnter:`. If it returns false, this interaction will ignore this session. (We may ask again if something significant about the session changes, like the items in it.)

Note that returning true does not mean that the delegate definitely *will* accept this drop, just that it *might* want to accept the drop. To accept it, you must also implement `-dropInteraction:sessionDidUpdate:` and return a UIDropProposal with an appropriate operation.

This method is commonly used to check whether the session contains any items that this delegate can consume. Use `UIDropSession`'s convenience methods `-hasItemsConformingToTypeIdentifiers:`, `-canLoadObjectsOfClass:`, etc.

dropInteractionConcludeDrop

default void dropInteractionConcludeDrop(UIDropInteraction interaction,
                                         UIDropSession session)

Called when the user has dropped onto this interaction's view, after `-dropInteraction:performDrop:` has been called, and all resulting drop animations have completed.

The delegate should cause the interaction's view to draw in its final post-drop state.

dropInteractionItemWillAnimateDropWithAnimator

default void dropInteractionItemWillAnimateDropWithAnimator(UIDropInteraction interaction,
                                                            UIDragItem item,
                                                            UIDragAnimating animator)

Called when the drop animation is about to start, once for each item, whether it is visible or not. Use the animator to animate your own changes alongside the system animation.

dropInteractionPerformDrop

default void dropInteractionPerformDrop(UIDropInteraction interaction,
                                        UIDropSession session)

Called when the user drops onto this interaction's view. The delegate should now request data from the session's items' item providers. Data may be requested *only* during the scope of this method.

dropInteractionPreviewForDroppingItemWithDefault

default UITargetedDragPreview dropInteractionPreviewForDroppingItemWithDefault(UIDropInteraction interaction,
                                                                               UIDragItem item,
                                                                               UITargetedDragPreview defaultPreview)

Called when the drop happens, after `-dropInteraction:performDrop:`, once for each visible item. Provide a preview to animate the item to where it belongs. We provide `defaultPreview` which would leave the current preview where the item was dropped. You may return: - defaultPreview, to use it as-is - nil, to fade and shrink the drag item in place - [defaultPreview retargetedPreviewWithTarget:] to move the preview to a different target - a UITargetedDragPreview that you create however you like

dropInteractionSessionDidEnd

default void dropInteractionSessionDidEnd(UIDropInteraction interaction,
                                          UIDropSession session)

When the drag session ends, for any reason, this method will be called for *every* interaction that ever received `-dropInteraction:sessionDidEnter:`, `-dropInteraction:sessionDidUpdate:`, or `-dropInteraction:sessionDidExit:`.

If you were keeping track of the session for any reason, you may now forget it.

dropInteractionSessionDidEnter

default void dropInteractionSessionDidEnter(UIDropInteraction interaction,
                                            UIDropSession session)

Called when a drag enters the view.

dropInteractionSessionDidExit

default void dropInteractionSessionDidExit(UIDropInteraction interaction,
                                           UIDropSession session)

Called when the drag has exited the interaction's view.

dropInteractionSessionDidUpdate

default UIDropProposal dropInteractionSessionDidUpdate(UIDropInteraction interaction,
                                                       UIDropSession session)

Called when the drag enters the interaction's view, or when when the drag moves while inside the view, or if items are added to the drag while inside the view.

You *must* implement this method to accept a drop. Return a `UIDropProposal` that contains the operation that the delegate would like to perform. (Note that you may use `UIDropOperationMove` only if session.allowsMoveOperation is true.)

You may also set other properties on the `UIDropProposal` to change the appearance of the drag over this view.

Use the session's `-locationInView:` to get a point to use for hit testing.