CODEWITHSUNDEEP
iosiphoneuitableviewcore-data
Ticko
Ticko

Reputation: 398

Scrolling tableview while updating its datasource fetched from CoreData crash

Here is my context:

When I launch my app I fetch local data from CoreData and fill a tableview with it. At the same time I send an asynchronous request to my webservice to fetch what will be the new content of my tableview. As soon as the request sends me a response I delete all the instances of the current NSManagedObjects and create new ones with the new data I got. Then I replace the datasource of my tableview to an array of the new NSManagedObjectContexts instances.

My problem:

I'm getting an error : CoreData could not fulfill a fault for ... if I scroll my tableview when the request finished and is triggering the deletion/creation of my tableview's data source.

I understand that this problem occurs because I'm trying to access an old NSManagedObject instance while doesn't exist anymore as it is explained in the doc : Apple doc. But I have no idea of what are the best practices in my case.

I don't want to block the user until my request finished but I have to prevent any error if he accesses "old" data while the request didn't finish (e.g : what if the user taps on a cell and I pass an instance of an NSManagedObject to another viewcontroller but when the request finishes this object doesn't exist anymore ?)

I would appreciate any help !

Upvotes: 0

Views: 463

Answers (1)

Teo
Teo

Reputation: 3442

I highly recommend you to use NSFetchedResultsController since it's sole purpuse is:

You use a fetched results controller to efficiently manage the results returned from a Core Data fetch request to provide data for a UITableView object.

When using a fetched results controller it is much easier to handle the Core Data events like insert, delete, update.

You say you have three sections in your table view? That's no problem, NSFetchedResultsController can handle all of that.

Take a look at this. Apple provides a very nice set of instructions on how to configure and use NSFetchedResultsController.

Upvotes: 1

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