iOS Core Data NSPersistentStoreCoordinator never opened database

Question

I've got some weird problems with Core Data in my iOS which I cannot seem to reproduce, it just happens from time to time with some users that report it. The error I get from my iOS crash reports:

CoreData: -[NSPersistentStoreCoordinator _coordinator_you_never_successfully_opened_the_database_so_saving_back_to_it_is_kinda_hard:] + 56

Here is a screenshot (left out the product name):

The hard thing is that I don't get any search results on that error. Here is my (relevant) code:

saving:

-(void)save
{
    if(!self.horecaMOC.hasChanges)return;
    NSError *error;
    [self.horecaMOC save:&error];
    if(error)
    {
        NSLog(@"save error %@",error.localizedDescription);
    }
}

MOC:

-(NSManagedObjectContext*)horecaMOC
{
    if(!_horecaMOC)
    {
        NSPersistentStoreCoordinator *coordinator = self.horecaPSC;
        if (coordinator != nil) {
            _horecaMOC = [[NSManagedObjectContext alloc] init];
            [_horecaMOC setPersistentStoreCoordinator:coordinator];
        }
    }
    return _horecaMOC;
}

PSC:

-(NSPersistentStoreCoordinator*)horecaPSC
{
    if(!_horecaPSC)
    {
        NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"horeca.sqlite"];

        NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                                 [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                                 [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
                                 nil];

        NSError *error = nil;
        _horecaPSC = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.horecaMOM];
        if (![_horecaPSC addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }

    }
    return _horecaPSC;
}

MOM:

-(NSManagedObjectModel*)horecaMOM
{
    if(!_horecaMOM)
    {
        NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"poi" withExtension:@"momd"];
        _horecaMOM = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    }
    return _horecaMOM;
}

It seems like the setup is OK here, because 99% of the time it works, but sometimes I get that error that I did not open the database. Since I can't debug it's hard to figure out what's the cause. Might the PSC nil? And why would that then be? Also, I know that a MOC should be bound to 1 thread only, and since I can't get it to crash I don't think there could be an issue regarding this?

Thanks for any advice!

Microprint

[[NSManagedObjectContext alloc] init] is not the recommended way to create a MOC - you should use initWithConcurrencyType:, unless you have a very specific reason to use the former (e.g. in a NSOperation context). Re your issue, you should add some NSAssert statements in the getters and make sure that properties are not nil when they're required. Also, make sure you're setting the persistent store coordinator on a MOC using either -[NSManagedObjectContext performBlock:] or -[NSManagedObjectContext performBlockAndWait:]. – Thorndike

+1 to @MatteoPacini, if this happens from time to time and can't be easily reproduced, it's probably a race condition of some kind, which is likely since you're not handling concurrency correctly. – Pretoria

I'll give it a shot, thnx guys – Microprint

hey buddy, did you find any solution. I am getting the same issue and getting mad why the crashes are happening. – Excited