IGListUpdatingDelegate
Objective-C
@protocol IGListUpdatingDelegate <NSObject>
Swift
protocol ListUpdatingDelegate : NSObjectProtocol
Implement this protocol in order to handle both section and row based update events. Implementation should forward or coalesce these events to a backing store or collection.
-
Asks the delegate for the pointer functions for looking up an object in a collection.
Note
Since the updating delegate is responsible for transitioning between object sets, it becomes the “source of truth” for how objects and their corresponding section controllers are mapped. This allows the updater to control if objects are looked up by pointer, or more traditionally, with
-hash
/-isEqual
.For behavior similar to
NSDictionary
, simply return+[NSPointerFunctions pointerFunctionsWithOptions:NSPointerFunctionsObjectPersonality]
.Declaration
Objective-C
- (nonnull NSPointerFunctions *)objectLookupPointerFunctions;
Swift
func objectLookupPointerFunctions() -> NSPointerFunctions
Return Value
Pointer functions for looking up an object in a collection.
-
Perform a section update from an old array of objects to a new one.
Note
Implementations determine how to transition between objects. You can perform a diff on the objects, reload each section, or simply call
-reloadData
on the collection view. In the end, the collection view must be setup with a section for each object in thetoObjects
array.The
applySectionDataBlock
block should be called prior to making anyUICollectionView
updates, passing in thetoObjects
that the updater is applying.Declaration
Objective-C
- (void)performUpdateWithCollectionViewBlock: (nonnull IGListCollectionViewBlock)collectionViewBlock animated:(BOOL)animated sectionDataBlock:(nonnull IGListTransitionDataBlock) sectionDataBlock applySectionDataBlock: (nonnull IGListTransitionDataApplyBlock) applySectionDataBlock completion:(nullable IGListUpdatingCompletion) completion;
Swift
func performUpdate(collectionViewBlock: @escaping ListCollectionViewBlock, animated: Bool, sectionDataBlock: @escaping ListTransitionDataBlock, applySectionDataBlock: @escaping ListTransitionDataApplyBlock) async -> Bool
Parameters
collectionViewBlock
A block returning the collecion view to perform updates on.
animated
A flag indicating if the transition should be animated.
sectionDataBlock
A block that returns the section information (ex: from and to objects)
applySectionDataBlock
A block that must be called when the adapter applies changes to the collection view.
completion
A completion block to execute when the update is finished.
-
Perform an item update block in the collection view.
Declaration
Objective-C
- (void)performUpdateWithCollectionViewBlock: (nonnull IGListCollectionViewBlock)collectionViewBlock animated:(BOOL)animated itemUpdates: (nonnull IGListItemUpdateBlock)itemUpdates completion:(nullable IGListUpdatingCompletion) completion;
Swift
func performUpdate(collectionViewBlock: @escaping ListCollectionViewBlock, animated: Bool, itemUpdates: @escaping ListItemUpdateBlock) async -> Bool
Parameters
collectionViewBlock
A block returning the collecion view to perform updates on.
animated
A flag indicating if the transition should be animated.
itemUpdates
A block containing all of the updates.
completion
A completion block to execute when the update is finished.
-
Perform a
[UICollectionView setDataSource:...]
swap within this block. It gives the updater the chance to cancel or execute any on-going updates. The block should be executed synchronously.Declaration
Objective-C
- (void)performDataSourceChange:(nonnull IGListDataSourceChangeBlock)block;
Swift
func performDataSourceChange(_ block: @escaping ListDataSourceChangeBlock)
Parameters
block
The block that will actuallty change the
dataSource
-
Completely reload data in the collection.
Declaration
Objective-C
- (void)reloadDataWithCollectionViewBlock: (nonnull IGListCollectionViewBlock)collectionViewBlock reloadUpdateBlock: (nonnull IGListReloadUpdateBlock)reloadUpdateBlock completion:(nullable IGListUpdatingCompletion) completion;
Swift
func reloadData(collectionViewBlock: @escaping ListCollectionViewBlock, reloadUpdate reloadUpdateBlock: @escaping ListReloadUpdateBlock) async -> Bool
Parameters
collectionViewBlock
A block returning the collecion view to reload.
reloadUpdateBlock
A block that must be called when the adapter reloads the collection view.
completion
A completion block to execute when the reload is finished.
-
Tells the delegate to perform item inserts at the given index paths.
Declaration
Objective-C
- (void)insertItemsIntoCollectionView:(nonnull UICollectionView *)collectionView indexPaths: (nonnull NSArray<NSIndexPath *> *)indexPaths;
Swift
func insertItems(into collectionView: UICollectionView, indexPaths: [IndexPath])
Parameters
collectionView
The collection view on which to perform the transition.
indexPaths
The index paths to insert items into.
-
Tells the delegate to perform item deletes at the given index paths.
Declaration
Objective-C
- (void)deleteItemsFromCollectionView:(nonnull UICollectionView *)collectionView indexPaths: (nonnull NSArray<NSIndexPath *> *)indexPaths;
Swift
func deleteItems(from collectionView: UICollectionView, indexPaths: [IndexPath])
Parameters
collectionView
The collection view on which to perform the transition.
indexPaths
The index paths to delete items from.
-
Tells the delegate to move an item from and to given index paths.
Declaration
Objective-C
- (void)moveItemInCollectionView:(nonnull UICollectionView *)collectionView fromIndexPath:(nonnull NSIndexPath *)fromIndexPath toIndexPath:(nonnull NSIndexPath *)toIndexPath;
Swift
func moveItem(in collectionView: UICollectionView, from fromIndexPath: IndexPath, to toIndexPath: IndexPath)
Parameters
collectionView
The collection view on which to perform the transition.
fromIndexPath
The source index path of the item to move.
toIndexPath
The destination index path of the item to move.
-
Tells the delegate to reload an item from and to given index paths.
Note
Since UICollectionView is unable to handle calling -[UICollectionView reloadItemsAtIndexPaths:] safely while also executing insert and delete operations in the same batch updates, the updater must know about the origin and destination of the reload to perform a safe transition.
Declaration
Objective-C
- (void)reloadItemInCollectionView:(nonnull UICollectionView *)collectionView fromIndexPath:(nonnull NSIndexPath *)fromIndexPath toIndexPath:(nonnull NSIndexPath *)toIndexPath;
Swift
func reloadItem(in collectionView: UICollectionView, from fromIndexPath: IndexPath, to toIndexPath: IndexPath)
Parameters
collectionView
The collection view on which to perform the transition.
fromIndexPath
The source index path of the item to reload.
toIndexPath
The destination index path of the item to reload.
-
Tells the delegate to move a section from and to given indexes.
Declaration
Objective-C
- (void)moveSectionInCollectionView:(nonnull UICollectionView *)collectionView fromIndex:(NSInteger)fromIndex toIndex:(NSInteger)toIndex;
Swift
func moveSection(in collectionView: UICollectionView, from fromIndex: Int, to toIndex: Int)
Parameters
collectionView
The collection view on which to perform the transition.
fromIndex
The source index of the section to move.
toIndex
The destination index of the section to move.
-
Completely reload each section in the collection view.
Declaration
Objective-C
- (void)reloadCollectionView:(nonnull UICollectionView *)collectionView sections:(nonnull NSIndexSet *)sections;
Swift
func reload(_ collectionView: UICollectionView, sections: IndexSet)
Parameters
collectionView
The collection view to reload.
sections
The sections to reload.
-
True if the updater is currently updating the source of truth, like executing applySectionDataBlock and itemUpdates just before updating the UICollectionView.
Declaration
Objective-C
- (BOOL)isInDataUpdateBlock;
Swift
func isInDataUpdateBlock() -> Bool