Initializing the core data stack in the app delegate

gistfile1.m

@interface PCAppDelegate ()

@property PCPersistentStack *persistentStack;

@end

@implementation PCAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
	self.persistentStack = [[PCPersistentStack alloc] initWithStoreURL:[self storeURL] modelURL:[self modelURL]];
	UINavigationController* navigationController = (UINavigationController *)self.window.rootViewController;
	PCLeadsViewController *leadsViewController = (PCLeadsViewController *)navigationController.topViewController;
	leadsViewController.managedObjectContext = self.persistentStack.managedObjectContext;
    return YES;
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    [self.persistentStack saveContext];
}
							
- (NSURL*)storeURL {
    NSURL* documentsDirectory = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:YES error:NULL];
    return [documentsDirectory URLByAppendingPathComponent:@"db.sqlite"];
}

- (NSURL*)modelURL {
    return [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"];
}