The current ASCollectionNode data source API very closely parallels UIKit’s, and it suffers from the same problems. We can do much better. The objectives are:
Use node controllers to represent collection items, and have them survive across updates.
Provide node controllers with API to handle common events(e.g. selection).
Provide node controllers with API to talk to higher controllers(e.g. section controllers, view controllers).
Provide support for updating cell node contents instead of reloading cells.
Make it easier to safely pipe model data to node controllers.
Public API: Object-NodeController Data Source API
Add optional methods to ASCollectionDataSource :
/**
* Called synchronously on main thread when items are inserted. User returns arbitraryobject representing the current version of the item data.
*
* @param collectionNode The sender.
* @param indexPath The index path of the object to retrieve.
* @return The object that represents this item.
Note: We will continue to support collectionNode:nodeBlockForItemAtIndexPath:
Internal Changes to Support New Data Source API
Update ASCollectionElement instead to have initWithObject: and initWithNodeBlock: which would be selected based on the data source API that the user used.
Add a step in ASDataController on the editing queue to:
For inserted items: Request node controllers, assign them objects, assign node controller to element.
For updated items: Attempt to update the node controllers, request new node controllers for any that cannot be updated, assign node controller to element.
Note: Need to support hosting a new node in an existing cell.
Public API: Object-NodeController Data Source API
/** * Called synchronously on main thread when items are inserted. User returns arbitraryobject representing the current version of the item data. * * @param collectionNode The sender. * @param indexPath The index path of the object to retrieve. * @return The object that represents this item. */- (id)collectionNode:(ASCollectionNode *)collectionNode objectAtIndexPath:(NSIndexPath *)indexPath;
/** * Called asynchronously after objects are gathered. User creates and returns an appropriate node controller for the given object. */- (ASNodeController *)collectionNode:(ASCollectionNode *)node nodeControllerForObject:(id)object;Public API: Node Controller Cell Updating Methods
@interface ASNodeController (CollectionViewItemMethods)
/** * The index path of the item, if any, that this node controller is at in its collection. */@property (copy, nullable, readonly) NSIndexPath *indexPath;
/** * The object currently assigned to this node controller, if any. */@property (strong, nullable, readonly) id object;