ニフティクラウドmobile backendのUnity SDKで匿名ログイン処理 ref: https://qiita.com/kajitack/items/3ca88a20817962684a8c

file0.cs

using UnityEngine;
using System;
using System.Collections;

public class UUIDManager : SingletonMonoBehaviour<UUIDManager> {
    Guid guid;
    [SerializeField]
    string _uuid = "";
    public string uuid {
        get {
            if ( _uuid == "" && HasUUID() ) {
                Load();
            }
            return _uuid;
        }
        private set {
            _uuid = value;
        }
    }

    void Start () {
        if ( !HasUUID() ) {
            Create();
            Save();
        } else if (uuid == "")  {
            Load();
        }
    }

    public void Create() {
        guid = Guid.NewGuid();
        uuid = guid.ToString();
    }

    public void Save() {
        PlayerPrefs.SetString("uuid",uuid);
        PlayerPrefs.Save();
        Debug.Log("uuid Save");
    }

    public void Load() {
        uuid = PlayerPrefs.GetString("uuid");
        Debug.Log("uuid Load");
    }

    public void Delete() {
        PlayerPrefs.DeleteKey("uuid");
    }

    public bool HasUUID() {
        if (PlayerPrefs.GetString("uuid").Length > 0) 
            return true;
        return false;
    }

}

file1.cs

using UnityEngine;
using System;
using System.Collections;
using NCMB;

public class UserAuth : SingletonMonoBehaviour<UserAuth> {
    // パスワードは適当に設定
    static string PASSWORD = "zwDyWpnKZx74xdayyhs34s"; 

    public void AnonymousLogin() {
        string id = UUIDManager.Instance.uuid;
        string pw = PASSWORD;
        NCMBUser.LogInAsync (id, pw, (NCMBException e) => {
            if( e == null ){
                Debug.Log("anonymous login");
            } else if (e.ErrorCode == NCMBException.INCORRECT_PASSWORD) {
                // ユーザーがDBに登録されていない場合は登録する
                AnonymousSignup();
            }
        });
    }

    public void AnonymousSignup() {
        NCMBUser user = new NCMBUser();
        user.UserName = UUIDManager.Instance.uuid;
        user.Password = PASSWORD;
        NCMBACL acl = new NCMBACL();
        acl.SetWriteAccess("*",true);
        acl.SetReadAccess("*",true);
        user.ACL = acl;
        user.SignUpAsync((NCMBException e) => { 
            if( e == null ){
                Debug.Log("anonymous signup");
            }
        });
    }

    public void Logout() {
        NCMBUser.LogOutAsync ( (NCMBException e) => {
            if( e == null ){
                Debug.Log("logout");
            }
        });
    }
}

file2.cs

using UnityEngine;
using System.Collections;

public class LoginManager : MonoBehaviour {
    public void Start () {
        // 起動時に匿名ログイン
        UserAuth.Instance.AnonymousLogin();
    }
    void OnApplicationQuit() {
        // アプリ終了時にログアウト
        UserAuth.Instance.Logout();
    }
}