CODEWITHSUNDEEP
iosobjective-ccore-data
user1444387
user1444387

Reputation: 53

IOS : Remove a Persistent Storage in a Multithreading CoreData Implementation

Multithreading is definitely a tricky thing.

I have a Main Thread (AppDelegate), and then my app starts to send several other requests to sync some data according to some user actions. The data reads and modifies the CoreData. A Managed Object Conext is being created in each thread as Apple says.

Problem is, the "reset data base feature". That one that will simply remove all the data stored locally.

I'm doing that by removing the Persistent Store in the AppDelegate like so:

- (bool) resetCoreData
{

    //Remove the persistent Store.
    NSError *error;
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"insight.sqlite"];
    [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil];

    //Borrar los conextos para que el APP lo cree despues
    for (NSManagedObject *ct in [self.managedObjectContext registeredObjects]) {
        [self.managedObjectContext deleteObject:ct];
    }



    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:

                             [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,

                             [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];

    //Make new persistent store for future saves
    if (![self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
        // TODO: handling
    }

    return true;

}

Then, if try to fetch data from some other thread:

 *** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x1edba090 <x-coredata://5EAC46F6-54DA-480B-9B15-CB28248FD1CE/PlanResults/p7>''

Thoughts?

Upvotes: 1

Views: 149

Answers (1)

bbarnhart
bbarnhart

Reputation: 6710

You need to release all NSManagedObjectContext objects before you delete your NSPersistentStoreCoordinator object. This needs to happen for all NSManagedObjectContext objects in all threads. NSManagedObjectContext objects have a persistentStoreCoordinator property.

After deleting the NSPersistentStoreCoordinator file you can then re-create the NSManagedObjectContext objects.

Upvotes: 1

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