WrapingFunctionsWithPromise.swift

func promiseFetchUserData(user: [String: Any]) -> Promise<User> {
        return Promise<User> { seal in
            fetchUserData(for: user, completion: { (response, results, error) in
                switch response {
                case .success:
                    seal.fulfill(results)
                case .fail:
                    seal.reject(error)
                }
            })
        }
    }
    
    func promiseLoginUser(user: User) -> Promise<Bool> {
        return Promise<Bool> { seal in
            loginUser(user: user, completion: { (response, resolts, error) in
                switch response {
                case .success:
                    seal.fulfill(true)
                case .fail:
                    seal.reject(error)
                }
            })
        }
    }