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ioscore-datansfetchedresultscontrollernsmanagedobjectcontext

Update UITableView when related NSManagedObject is updated

I have following relationship hierarchy between core-data entities (managed objects):

Entity1 > Entity2 > Entity3

There's a one-to-one relationship between Entity1 and Entity2, and one-to-many relationship between Entity2 and Entity3.

I have a view controller that displays a list of Entity1 records, using NSFetchedResultsController. The UITableViewCell shows information from Entity1, Entity2 and Entity3. Now, the NSFetchedResultsControllerDelegate methods are automatically called when Entity1 object is added/updated/deleted, BUT when the related Entity2 or Entity3 records are added/updated/deleted, the delegate methods are not called.

In this situation, what's the best or possible way to recognize that related records have been updated, and that UITableViewCell needs to be updated as well?

Solution

  • You need to make dirty the properties of the other entities. In other words, you should call

    [self willChangeValueForKey:@"someProperty"];
[self didChangeValueForKey:@"someProperty"];

    on the entities you want to update.

    Here a sample solution that makes possible what you want to achieve.

    NSFetchedResultsController pitfall

    Hope that helps.