Boilerplate code for Core Data project

gistfile1.m

    - (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;
        }
        else
        {
            _managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
            return _managedObjectModel;
        }
    }
    - (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
        if (_persistentStoreCoordinator != nil) {
            return _persistentStoreCoordinator;
        }
        NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"Model.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;
    }
    
    - (NSString *)applicationDocumentsDirectory
    {
        return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    }