RestKit saveToPersistentStore doesnt work

Question

I am using RestKit for my rest implementation. I fetch the data from the server and upon receiving it, I call saveToPersistentStore which is successful as well but when I turn off internet and load that page again, it doesnt find any data in the store.

Here is the initialization flow -

NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Storage" ofType:@"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
NSAssert(persistentStore, @"Failed to add persistent store: %@", error);

[managedObjectStore createManagedObjectContexts];

// Set the default store shared instance
[RKManagedObjectStore setDefaultStore:managedObjectStore];

I use the mainQueue for everythng -

    controller.managedObjectContext = managedObjectStore.mainQueueManagedObjectContext;

This is the function which does the fetch:

[CMLRKSharedManager getNewsForUser:userProfile
                             urlParams:dict
                               success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
       [self.tableView reloadData];
       NSLog(@"Fetched object count %lu %@ %@", (unsigned long)self.fetchedResultsController.fetchedObjects.count , self.fetchedResultsController, self.fetchedResultsController.managedObjectContext);
       NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;

       NSError *executeError = nil;
       if(![managedObjCtx saveToPersistentStore:&executeError]) {
           NSLog(@"Failed to save to data store");
        }
       else
           NSLog(@"SAVE SUCCESSFUL");
    } failure:^(RKObjectRequestOperation *operation, NSError *error) {
        [self.tableView reloadData];
    }];
}

Output:

2014-04-02 22:24:01.547 Fetched object count 4

2014-04-02 22:24:01.555 SAVE SUCCESSFUL

Now I kill the app, turn off wifi and launch app again. The table is now blank and I see that the fetchResultsController is seeing 0 items in console log

Apr 2 22:24:36 : In numberOfRows Fetched object count 0

I'm not sure why...

@wain I update the code as follows -

NSError *error = nil;
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Cover" ofType:@"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

Commented these 2 lines

//    NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
//    NSAssert(persistentStore, @"Failed to add persistent store: %@", error);
//    

Instead added the sqlite db but now the app crashed

BOOL success = RKEnsureDirectoryExistsAtPath(RKApplicationDataDirectory(), &error);
if (! success) {
    RKLogError(@"Failed to create Application Data Directory at path '%@': %@", RKApplicationDataDirectory(), error);
}
NSString *path = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"Store.sqlite"];
NSPersistentStore *persistentStore = [managedObjectStore addSQLitePersistentStoreAtPath:path fromSeedDatabaseAtPath:nil withConfiguration:nil options:nil error:&error];
if (! persistentStore) {
    RKLogError(@"Failed adding persistent store at path '%@': %@", path, error);
}

Answer 1

From your description, the issue is that you only have an in-memory store:

[managedObjectStore addInMemoryPersistentStore:&error];

so nothing is saved to disk. You should change this so that you are using an SQLite store. This will save data to disk and generally work better in most usage scenarios.