Question

I’m attempting to build my first Core Data app but am running into problems at startup when the app crashes with the following error:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an entity named 'Launchpad' in this model.'
*** First throw call stack:
(0x15b7012 0x13dce7e 0x6f4c5 0x3e0f 0x3c64 0xee05c8 0xe4802a 0xe15d23 0xe15a34 0xea2301 0x21ba53f 0x21cc014 0x21bc7d5 0x155daf5 0x155cf44 0x155ce1b 0x24037e3 0x2403668 0x32465c 0x2abd 0x29e5 0x1)
libc++abi.dylib: terminate called throwing an exception

I’ve been researching this error and I’ve gathered that generally caused because I’ve not fully configured the managedObjectModel correctly, but I’m not sure how to spot such an error in my own code.

I have the following three functions in my AppDelegate:

- (NSManagedObjectContext *)managedObjectContext
{
    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {
        _managedObjectContext = [[NSManagedObjectContext alloc] init];
        [_managedObjectContext setPersistentStoreCoordinator:coordinator];
    }
    return _managedObjectContext;
}

- (NSManagedObjectModel *)managedObjectModel
{
    if (_managedObjectModel != nil) {
        return _managedObjectModel;
    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Orbiter" withExtension:@"momd"];
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    return _managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Orbiter.sqlite"];

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

    return _persistentStoreCoordinator;
}

To my untrained eye it appears as if my Core Data objects are being properly configured.

I’ve added an entity called Launchpad to my xcdatamodeld file and connected it to the corresponding class called Launchpad which derives from NSManagedObject.

The snippet of code that’s causing the crash is

AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSManagedObject *launchpad = [NSEntityDescription insertNewObjectForEntityForName:@"Launchpad" inManagedObjectContext:context];

where the last line is where things come off the rails.

I’ve looked around and all the help I’ve found suggests I add the functions that I already have in my AppDelegate, so I really have no idea where to go from here.

Answer 1

This is always going to be a problem when ever you change the data model, an easy way would be to change your code to automatically migrate data without you always reinstalling the app and loosing the data you already populated.

In the place where you created the persistent store you can do some thing like this and it will automatically move the data for you for your new models and make sure that you do not loose all your old data. You can read about managed object mapping if you want to explicitly map the old model to the new model.

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

_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error])