UICollectionViewDelegate (moe.platform.ios API)

All Superinterfaces:

UIScrollViewDelegate

All Known Subinterfaces:

UICollectionViewDelegateFlowLayout

All Known Implementing Classes:

UICollectionViewController
```
public interface UICollectionViewDelegate
extends UIScrollViewDelegate
```

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method and Description
`default boolean`	`collectionViewCanEditItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Editing Asks the delegate to verify that the given item is editable.
`default boolean`	`collectionViewCanFocusItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Focus
`default boolean`	`collectionViewCanPerformActionForItemAtIndexPathWithSender(UICollectionView collectionView, org.moe.natj.objc.SEL action, NSIndexPath indexPath, java.lang.Object sender)`
`default UIContextMenuConfiguration`	`collectionViewContextMenuConfigurationForItemAtIndexPathPoint(UICollectionView collectionView, NSIndexPath indexPath, CGPoint point)` Called when the interaction begins.
`default void`	`collectionViewDidBeginMultipleSelectionInteractionAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Called right after allowsMultipleSelection is set to YES if -collectionView:shouldBeginMultipleSelectionInteractionAtIndexPath: returned YES.
`default void`	`collectionViewDidDeselectItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)`
`default void`	`collectionViewDidEndDisplayingCellForItemAtIndexPath(UICollectionView collectionView, UICollectionViewCell cell, NSIndexPath indexPath)`
`default void`	`collectionViewDidEndDisplayingSupplementaryViewForElementOfKindAtIndexPath(UICollectionView collectionView, UICollectionReusableView view, java.lang.String elementKind, NSIndexPath indexPath)`
`default void`	`collectionViewDidEndMultipleSelectionInteraction(UICollectionView collectionView)` Called when the multi-select interaction ends.
`default void`	`collectionViewDidHighlightItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)`
`default void`	`collectionViewDidSelectItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)`
`default void`	`collectionViewDidUnhighlightItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)`
`default void`	`collectionViewDidUpdateFocusInContextWithAnimationCoordinator(UICollectionView collectionView, UICollectionViewFocusUpdateContext context, UIFocusAnimationCoordinator coordinator)`
`default void`	`collectionViewPerformActionForItemAtIndexPathWithSender(UICollectionView collectionView, org.moe.natj.objc.SEL action, NSIndexPath indexPath, java.lang.Object sender)`
`default UITargetedPreview`	`collectionViewPreviewForDismissingContextMenuWithConfiguration(UICollectionView collectionView, UIContextMenuConfiguration configuration)` Called when the interaction is about to dismiss.
`default UITargetedPreview`	`collectionViewPreviewForHighlightingContextMenuWithConfiguration(UICollectionView collectionView, UIContextMenuConfiguration configuration)` Called when the interaction begins.
`default UIWindowSceneActivationConfiguration`	`collectionViewSceneActivationConfigurationForItemAtIndexPathPoint(UICollectionView collectionView, NSIndexPath indexPath, CGPoint point)` Return a valid @c UIWindowSceneActivationConfiguration to allow for the cell to be expanded into a new scene.
`default boolean`	`collectionViewSelectionFollowsFocusForItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Determines if the item at the specified index path should also become selected when focus moves to it.
`default boolean`	`collectionViewShouldBeginMultipleSelectionInteractionAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Allows a two-finger pan gesture to automatically enable allowsMultipleSelection and start selecting multiple cells.
`default boolean`	`collectionViewShouldDeselectItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` called when the user taps on an already-selected item in multi-select mode
`default boolean`	`collectionViewShouldHighlightItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` Methods for notification of selection/deselection and highlight/unhighlight events.
`default boolean`	`collectionViewShouldSelectItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)`
`default boolean`	`collectionViewShouldShowMenuForItemAtIndexPath(UICollectionView collectionView, NSIndexPath indexPath)` These methods provide support for copy/paste actions on cells.
`default boolean`	`collectionViewShouldSpringLoadItemAtIndexPathWithContext(UICollectionView collectionView, NSIndexPath indexPath, UISpringLoadedInteractionContext context)` Allows opting-out of spring loading for an particular item.
`default boolean`	`collectionViewShouldUpdateFocusInContext(UICollectionView collectionView, UICollectionViewFocusUpdateContext context)`
`default CGPoint`	`collectionViewTargetContentOffsetForProposedContentOffset(UICollectionView collectionView, CGPoint proposedContentOffset)` customize the content offset to be applied during transition or update animations
`default NSIndexPath`	`collectionViewTargetIndexPathForMoveFromItemAtIndexPathToProposedIndexPath(UICollectionView collectionView, NSIndexPath currentIndexPath, NSIndexPath proposedIndexPath)`
`default NSIndexPath`	`collectionViewTargetIndexPathForMoveOfItemFromOriginalIndexPathAtCurrentIndexPathToProposedIndexPath(UICollectionView collectionView, NSIndexPath originalIndexPath, NSIndexPath currentIndexPath, NSIndexPath proposedIndexPath)`
`default UICollectionViewTransitionLayout`	`collectionViewTransitionLayoutForOldLayoutNewLayout(UICollectionView collectionView, UICollectionViewLayout fromLayout, UICollectionViewLayout toLayout)` support for custom transition layout
`default void`	`collectionViewWillDisplayCellForItemAtIndexPath(UICollectionView collectionView, UICollectionViewCell cell, NSIndexPath indexPath)`
`default void`	`collectionViewWillDisplayContextMenuWithConfigurationAnimator(UICollectionView collectionView, UIContextMenuConfiguration configuration, UIContextMenuInteractionAnimating animator)` Called when the collection view is about to display a menu.
`default void`	`collectionViewWillDisplaySupplementaryViewForElementKindAtIndexPath(UICollectionView collectionView, UICollectionReusableView view, java.lang.String elementKind, NSIndexPath indexPath)`
`default void`	`collectionViewWillEndContextMenuInteractionWithConfigurationAnimator(UICollectionView collectionView, UIContextMenuConfiguration configuration, UIContextMenuInteractionAnimating animator)` Called when the collection view's context menu interaction is about to end.
`default void`	`collectionViewWillPerformPreviewActionForMenuWithConfigurationAnimator(UICollectionView collectionView, UIContextMenuConfiguration configuration, UIContextMenuInteractionCommitAnimating animator)` Called when the interaction is about to "commit" in response to the user tapping the preview.
`default NSIndexPath`	`indexPathForPreferredFocusedViewInCollectionView(UICollectionView collectionView)`

Methods inherited from interface apple.uikit.protocol.UIScrollViewDelegate
scrollViewDidChangeAdjustedContentInset, scrollViewDidEndDecelerating, scrollViewDidEndDraggingWillDecelerate, scrollViewDidEndScrollingAnimation, scrollViewDidEndZoomingWithViewAtScale, scrollViewDidScroll, scrollViewDidScrollToTop, scrollViewDidZoom, scrollViewShouldScrollToTop, scrollViewWillBeginDecelerating, scrollViewWillBeginDragging, scrollViewWillBeginZoomingWithView, scrollViewWillEndDraggingWithVelocityTargetContentOffset, viewForZoomingInScrollView

Method Detail

collectionViewCanFocusItemAtIndexPath

default boolean collectionViewCanFocusItemAtIndexPath(UICollectionView collectionView,
                                                      NSIndexPath indexPath)

Focus

collectionViewCanPerformActionForItemAtIndexPathWithSender

default boolean collectionViewCanPerformActionForItemAtIndexPathWithSender(UICollectionView collectionView,
                                                                           org.moe.natj.objc.SEL action,
                                                                           NSIndexPath indexPath,
                                                                           java.lang.Object sender)

collectionViewDidDeselectItemAtIndexPath

default void collectionViewDidDeselectItemAtIndexPath(UICollectionView collectionView,
                                                      NSIndexPath indexPath)

collectionViewDidEndDisplayingCellForItemAtIndexPath

default void collectionViewDidEndDisplayingCellForItemAtIndexPath(UICollectionView collectionView,
                                                                  UICollectionViewCell cell,
                                                                  NSIndexPath indexPath)

collectionViewDidEndDisplayingSupplementaryViewForElementOfKindAtIndexPath

default void collectionViewDidEndDisplayingSupplementaryViewForElementOfKindAtIndexPath(UICollectionView collectionView,
                                                                                        UICollectionReusableView view,
                                                                                        java.lang.String elementKind,
                                                                                        NSIndexPath indexPath)

collectionViewDidHighlightItemAtIndexPath

default void collectionViewDidHighlightItemAtIndexPath(UICollectionView collectionView,
                                                       NSIndexPath indexPath)

collectionViewDidSelectItemAtIndexPath

default void collectionViewDidSelectItemAtIndexPath(UICollectionView collectionView,
                                                    NSIndexPath indexPath)

collectionViewDidUnhighlightItemAtIndexPath

default void collectionViewDidUnhighlightItemAtIndexPath(UICollectionView collectionView,
                                                         NSIndexPath indexPath)

collectionViewDidUpdateFocusInContextWithAnimationCoordinator

default void collectionViewDidUpdateFocusInContextWithAnimationCoordinator(UICollectionView collectionView,
                                                                           UICollectionViewFocusUpdateContext context,
                                                                           UIFocusAnimationCoordinator coordinator)

collectionViewPerformActionForItemAtIndexPathWithSender

default void collectionViewPerformActionForItemAtIndexPathWithSender(UICollectionView collectionView,
                                                                     org.moe.natj.objc.SEL action,
                                                                     NSIndexPath indexPath,
                                                                     java.lang.Object sender)

collectionViewShouldDeselectItemAtIndexPath

default boolean collectionViewShouldDeselectItemAtIndexPath(UICollectionView collectionView,
                                                            NSIndexPath indexPath)

called when the user taps on an already-selected item in multi-select mode

collectionViewShouldHighlightItemAtIndexPath
```
default boolean collectionViewShouldHighlightItemAtIndexPath(UICollectionView collectionView,
                                                             NSIndexPath indexPath)
```
Methods for notification of selection/deselection and highlight/unhighlight events. The sequence of calls leading to selection from a user touch is:
(when the touch begins) 1. -collectionView:shouldHighlightItemAtIndexPath: 2. -collectionView:didHighlightItemAtIndexPath:
(when the touch lifts) 3. -collectionView:shouldSelectItemAtIndexPath: or -collectionView:shouldDeselectItemAtIndexPath: 4. -collectionView:didSelectItemAtIndexPath: or -collectionView:didDeselectItemAtIndexPath: 5. -collectionView:didUnhighlightItemAtIndexPath:

collectionViewShouldSelectItemAtIndexPath

default boolean collectionViewShouldSelectItemAtIndexPath(UICollectionView collectionView,
                                                          NSIndexPath indexPath)

collectionViewShouldShowMenuForItemAtIndexPath

default boolean collectionViewShouldShowMenuForItemAtIndexPath(UICollectionView collectionView,
                                                               NSIndexPath indexPath)

These methods provide support for copy/paste actions on cells. All three should be implemented if any are.

collectionViewShouldUpdateFocusInContext

default boolean collectionViewShouldUpdateFocusInContext(UICollectionView collectionView,
                                                         UICollectionViewFocusUpdateContext context)

collectionViewTargetContentOffsetForProposedContentOffset

default CGPoint collectionViewTargetContentOffsetForProposedContentOffset(UICollectionView collectionView,
                                                                          CGPoint proposedContentOffset)

customize the content offset to be applied during transition or update animations

collectionViewTargetIndexPathForMoveFromItemAtIndexPathToProposedIndexPath

default NSIndexPath collectionViewTargetIndexPathForMoveFromItemAtIndexPathToProposedIndexPath(UICollectionView collectionView,
                                                                                               NSIndexPath currentIndexPath,
                                                                                               NSIndexPath proposedIndexPath)

collectionViewTransitionLayoutForOldLayoutNewLayout

default UICollectionViewTransitionLayout collectionViewTransitionLayoutForOldLayoutNewLayout(UICollectionView collectionView,
                                                                                             UICollectionViewLayout fromLayout,
                                                                                             UICollectionViewLayout toLayout)

support for custom transition layout

collectionViewWillDisplayCellForItemAtIndexPath

default void collectionViewWillDisplayCellForItemAtIndexPath(UICollectionView collectionView,
                                                             UICollectionViewCell cell,
                                                             NSIndexPath indexPath)

collectionViewWillDisplaySupplementaryViewForElementKindAtIndexPath

default void collectionViewWillDisplaySupplementaryViewForElementKindAtIndexPath(UICollectionView collectionView,
                                                                                 UICollectionReusableView view,
                                                                                 java.lang.String elementKind,
                                                                                 NSIndexPath indexPath)

indexPathForPreferredFocusedViewInCollectionView

default NSIndexPath indexPathForPreferredFocusedViewInCollectionView(UICollectionView collectionView)

collectionViewShouldSpringLoadItemAtIndexPathWithContext

default boolean collectionViewShouldSpringLoadItemAtIndexPathWithContext(UICollectionView collectionView,
                                                                         NSIndexPath indexPath,
                                                                         UISpringLoadedInteractionContext context)

Allows opting-out of spring loading for an particular item.

If you want the interaction effect on a different subview of the spring loaded cell, modify the context.targetView property. The default is the cell.

If this method is not implemented, the default is YES.

collectionViewContextMenuConfigurationForItemAtIndexPathPoint
```
default UIContextMenuConfiguration collectionViewContextMenuConfigurationForItemAtIndexPathPoint(UICollectionView collectionView,
                                                                                                 NSIndexPath indexPath,
                                                                                                 CGPoint point)
```
Called when the interaction begins.

Parameters:

collectionView - This UICollectionView.

indexPath - IndexPath of the item for which a configuration is being requested.

point - Location in the collection view's coordinate space

Returns:

A UIContextMenuConfiguration describing the menu to be presented. Return nil to prevent the interaction from beginning. Returning an empty configuration causes the interaction to begin then fail with a cancellation effect. You might use this to indicate to users that it's possible for a menu to be presented from this element, but that there are no actions to present at this particular time.

collectionViewDidBeginMultipleSelectionInteractionAtIndexPath
```
default void collectionViewDidBeginMultipleSelectionInteractionAtIndexPath(UICollectionView collectionView,
                                                                           NSIndexPath indexPath)
```
Called right after allowsMultipleSelection is set to YES if -collectionView:shouldBeginMultipleSelectionInteractionAtIndexPath: returned YES.
In your app, this would be a good opportunity to update the state of your UI to reflect the fact that the user is now selecting multiple items at once; such as updating buttons to say "Done" instead of "Select"/"Edit", for instance.

collectionViewPreviewForDismissingContextMenuWithConfiguration
```
default UITargetedPreview collectionViewPreviewForDismissingContextMenuWithConfiguration(UICollectionView collectionView,
                                                                                         UIContextMenuConfiguration configuration)
```
Called when the interaction is about to dismiss. Return a UITargetedPreview describing the desired dismissal target. The interaction will animate the presented menu to the target. Use this to customize the dismissal animation.

Parameters:

collectionView - This UICollectionView.

configuration - The configuration of the menu displayed by this interaction.

collectionViewPreviewForHighlightingContextMenuWithConfiguration

default UITargetedPreview collectionViewPreviewForHighlightingContextMenuWithConfiguration(UICollectionView collectionView,
                                                                                           UIContextMenuConfiguration configuration)

Called when the interaction begins. Return a UITargetedPreview describing the desired highlight preview.

Parameters:: collectionView - This UICollectionView.; configuration - The configuration of the menu about to be displayed by this interaction.

collectionViewShouldBeginMultipleSelectionInteractionAtIndexPath
```
default boolean collectionViewShouldBeginMultipleSelectionInteractionAtIndexPath(UICollectionView collectionView,
                                                                                 NSIndexPath indexPath)
```
Allows a two-finger pan gesture to automatically enable allowsMultipleSelection and start selecting multiple cells.
After a multi-select gesture is recognized, this method will be called before allowsMultipleSelection is automatically set to YES to allow the user to select multiple contiguous items using a two-finger pan gesture across the constrained scroll direction.
If the collection view has no constrained scroll direction (i.e., the collection view scrolls both horizontally and vertically), then this method will not be called and the multi-select gesture will be disabled.
If this method is not implemented, the default is NO.

collectionViewWillPerformPreviewActionForMenuWithConfigurationAnimator

default void collectionViewWillPerformPreviewActionForMenuWithConfigurationAnimator(UICollectionView collectionView,
                                                                                    UIContextMenuConfiguration configuration,
                                                                                    UIContextMenuInteractionCommitAnimating animator)

Called when the interaction is about to "commit" in response to the user tapping the preview.

Parameters:: collectionView - This UICollectionView.; configuration - Configuration of the currently displayed menu.; animator - Commit animator. Add animations to this object to run them alongside the commit transition.

collectionViewDidEndMultipleSelectionInteraction
```
default void collectionViewDidEndMultipleSelectionInteraction(UICollectionView collectionView)
```
Called when the multi-select interaction ends.
At this point, the collection view will remain in multi-select mode, but this delegate method is called to indicate that the multiple selection gesture or hardware keyboard interaction has ended.

collectionViewCanEditItemAtIndexPath
```
default boolean collectionViewCanEditItemAtIndexPath(UICollectionView collectionView,
                                                     NSIndexPath indexPath)
```
Editing Asks the delegate to verify that the given item is editable.

Parameters:

collectionView - The collection view object requesting this information.

indexPath - An index path locating an item in `collectionView`.

Returns:

`YES` if the item is editable; otherwise, `NO`. Defaults to `YES`.

collectionViewWillDisplayContextMenuWithConfigurationAnimator

default void collectionViewWillDisplayContextMenuWithConfigurationAnimator(UICollectionView collectionView,
                                                                           UIContextMenuConfiguration configuration,
                                                                           UIContextMenuInteractionAnimating animator)

Called when the collection view is about to display a menu.

Parameters:: collectionView - This UICollectionView.; configuration - The configuration of the menu about to be displayed.; animator - Appearance animator. Add animations to run them alongside the appearance transition.

collectionViewWillEndContextMenuInteractionWithConfigurationAnimator

default void collectionViewWillEndContextMenuInteractionWithConfigurationAnimator(UICollectionView collectionView,
                                                                                  UIContextMenuConfiguration configuration,
                                                                                  UIContextMenuInteractionAnimating animator)

Called when the collection view's context menu interaction is about to end.

Parameters:: collectionView - This UICollectionView.; configuration - Ending configuration.; animator - Disappearance animator. Add animations to run them alongside the disappearance transition.

collectionViewSceneActivationConfigurationForItemAtIndexPathPoint

default UIWindowSceneActivationConfiguration collectionViewSceneActivationConfigurationForItemAtIndexPathPoint(UICollectionView collectionView,
                                                                                                               NSIndexPath indexPath,
                                                                                                               CGPoint point)

Return a valid @c UIWindowSceneActivationConfiguration to allow for the cell to be expanded into a new scene. Return nil to prevent the interaction from starting.

Parameters:: collectionView - The collection view; indexPath - The index path of the cell being interacted with; point - The centroid of the interaction in the collection view's coordinate space.

collectionViewSelectionFollowsFocusForItemAtIndexPath
```
default boolean collectionViewSelectionFollowsFocusForItemAtIndexPath(UICollectionView collectionView,
                                                                      NSIndexPath indexPath)
```
Determines if the item at the specified index path should also become selected when focus moves to it. If the collection view's global selectionFollowsFocus is enabled, this method will allow you to override that behavior on a per-index path basis. This method is not called if selectionFollowsFocus is disabled.

collectionViewTargetIndexPathForMoveOfItemFromOriginalIndexPathAtCurrentIndexPathToProposedIndexPath

default NSIndexPath collectionViewTargetIndexPathForMoveOfItemFromOriginalIndexPathAtCurrentIndexPathToProposedIndexPath(UICollectionView collectionView,
                                                                                                                         NSIndexPath originalIndexPath,
                                                                                                                         NSIndexPath currentIndexPath,
                                                                                                                         NSIndexPath proposedIndexPath)

Interface UICollectionViewDelegate