Question

I think I might be going crazy. In the following method, the return value _persistentStoreCoordinator is nil unless I add another line of code. Checking _persistentStoreCoordinator == nil is enough to make sure that it isn’t. (An NSLog statement will also do the trick.)

If I don’t add another line, _persistentStoreCoordinator is nil in the last line of the method, even though when inspecting it with break-points psc is always non-nil.

The strangest (or perhaps most helpful?) thing is that I didn’t make any changes to this class when the problems started.

Any help or explanations greatly appreciated!

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
    if (_persistentStoreCoordinator == nil) {
        NSLog(@"SQLITE STORE PATH: %@", [self pathToLocalStore]);
        NSURL *storeURL = [NSURL fileURLWithPath:[self pathToLocalStore]];
        NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc]
                                             initWithManagedObjectModel:[self managedObjectModel]];
        NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                                 [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                                 [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
        NSError *e = nil;
        if (![psc addPersistentStoreWithType:NSSQLiteStoreType
                               configuration:nil
                                         URL:storeURL
                                     options:options
                                       error:&e]) {
            NSDictionary *userInfo = [NSDictionary dictionaryWithObject:e forKey:NSUnderlyingErrorKey];
            NSString *reason = @"Could not create persistent store.";
            NSException *exc = [NSException exceptionWithName:NSInternalInconsistencyException
                                                       reason:reason
                                                     userInfo:userInfo];
            @throw exc;
        }

        _persistentStoreCoordinator = psc;
        if (_persistentStoreCoordinator == nil)
        {
            NSLog(@"We never reach here.");
        }
    }

    return _persistentStoreCoordinator;
}

Answer 1

Upon rechecking my .h file I saw that I was maintaining a weak reference to _persistantStoreCoordinator.

@property (weak, nonatomic, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;

Sure enough, changing the reference to strong fixed things.