func getAllUsers() {
        do {
            let fetchRequest = NSFetchRequest(entityName: "Users")

            if let fetchResults = try managedObjectContext.executeFetchRequest(fetchRequest) as? [Users] {
                print("users count: \(fetchResults.count)")

                for var i = 0; i < fetchResults.count; i++ {
                    let user = fetchResults[i] as Users

                    print(user.name)
                }
            }
        }
        catch {
            print("error")
        }
    }

    func checkUser(email: String, password: String) -> Bool {
        do {
            let fetchRequest = NSFetchRequest(entityName: "Users")

            let predicate = NSPredicate(format: "email == %@ and password == %@", email, password)

            fetchRequest.predicate = predicate

            if let fetchResults = try managedObjectContext.executeFetchRequest(fetchRequest) as? [Users] {
                if fetchResults.count > 0 {
                    return true
                }
                else {
                    return false
                }
            }
        }
        catch {
            print("error")
        }

        return false
    }

    func addUser(name: String, email: String, password: String) {
        do {
            let newItem = NSEntityDescription.insertNewObjectForEntityForName("Users", inManagedObjectContext: self.managedObjectContext) as! Users

            newItem.name = name
            newItem.email = email
            newItem.password = password

            try self.managedObjectContext.save()
        }
        catch {
            print("error")
        }
    }