user.signUpInBackground{ (success: Bool, error:Error?) in
    if success{
        print("signed up")
        UserDefaults.standard.set(user.username, forKey: "username")
        UserDefaults.standard.synchronize()
        user.signUpInBackground {(success: Bool, error: Error?) in
            if success {
                print("signed up")
                AVUser.logInWithUsername(inBackground: user.username!, password: user.password!, block: {(user: AVUser?, error: Error?) in
                    if let user = user {
                        UserDefaults.standard.set(user.username, forKey: "username")
                        UserDefaults.standard.synchronize()
                        let appDelegate: AppDelegate = UIApplication.shared.delegate as! AppDelegate
                        appDelegate.login()
                    }
                })
            }else {
                print(error!.localizedDescription)
            }
        }
    }
}