Open Radar

 
Please see another feedback FB9174006 making the same request but was submitted to the UIKit team.

In Xcode 13b1, UIDiffableDataSource.h has a new reconfigureItems method (see below). It would be great if this could be used in the NSFetchedResultsController snapshot API to replace reloadItems. 

In my experience reloading a cell when the NSManagedObject has been updated causes all kinds of visual glitches and bugs. E.g. if a user has swiped on a cell that is backed by a managed object that is updated, when the snapshot is used to update the table the cell jumps back to not being swiped. A similar issue happens if a cell was previously selected when the update happened. 

I have not tested it but it sounds to me like this reconfigureItems method could resolve all of these problems. I am aware though that it is possible when a managed object changes, someone might actually want to use a different cell entirely to display the updated object. I hope you can come up with a good solution to support both uses cases!

// Reconfigures any existing cells for the items. Reconfiguring is more efficient than reloading an item, as it does not replace the
// existing cell with a new cell. Prefer reconfiguring over reloading unless you actually need an entirely new cell for the item.
- (void)reconfigureItemsWithIdentifiers:(NSArray<ItemIdentifierType>*)identifiers API_AVAILABLE(ios(15.0), tvos(15.0));

I also really would like a method on NSFetchedResultsController to retrieve the current snapshot that I can apply to the table after the first performFetch without animation. Because it calls the delegate method for the first fetch and any updates, I have the inconvenience of needing to track if it is the first call so I can apply the update to the table without animation. However I am also experimenting with checking if the window handle is valid instead of using my own bool for that.