為什么字符串在Firebase中返回null

Question

//Anom loggin
    auth.SignInAnonymouslyAsync().ContinueWith(task =>
    {
        if (task.IsCanceled)
        {
            Debug.LogError("SignInAnonymouslyAsync was canceled.");
            return;
        }
        if (task.IsFaulted)
        {
            Debug.LogError("SignInAnonymouslyAsync encountered an error: " + task.Exception);
            return;
        }

        Firebase.Auth.FirebaseUser newUser = task.Result;
        Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId);

        userdataString = newUser.UserId;
        Debug.Log("userdatastring: " + userdataString);
    });

    Debug.Log("userdatastring out: " + userdataString);
}

當它離開匿名函數時，該值返回null，但在其中，如果返回我需要獲取的ID，則知道如何獲取字符串值嗎？

Answer 1

該firebase函數是一個異步函數，這意味着內部回調將在異步函數完成之前（處於成功或失敗狀態）都不會運行

這意味着您的調試日志實際上是在運行異步函數的回調之前運行的。

以下是您可以做的一些選擇：

1. 准備好后，讓Firebase異步函數調用回調函數。

    public void DoAnonymousSignIn(){ auth.SignInAnonymouslyAsync().ContinueWith(OnSignInDone); } private void OnSignInDone(Task<Firebase.Auth.FirebaseUser> task){ if (task.IsCanceled){ Debug.LogError("SignInAnonymouslyAsync was canceled."); return; } if (task.IsFaulted){ Debug.LogError("SignInAnonymouslyAsync encountered an error: " + task.Exception); return; } Firebase.Auth.FirebaseUser newUser = task.Result; Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId); userdataString = newUser.UserId; Debug.Log("userdatastring: " + userdataString); } 

2. 通過內聯處理回調而不是使用回調函數來保持它現在的狀態，或者設置一個將其標記為就緒的變量，或者直接從中調用“ SignInDone”函數（例如SignInSuccess（）和SignInFailed（））

3. 您還可以設置自己的回調事件，也可以從其他腳本中訂閱它們：

    using System; public static Action OnSignInSuccess; 

   然后在您的Firebase異步回調中，您可以執行以下操作：

     // ... within auth.SignInAnonymouslyAsync() callback Firebase.Auth.FirebaseUser newUser = task.Result; Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId); userdataString = newUser.UserId; if(OnSignInSuccess != null) OnSignInSuccess.Invoke(); } 

   然后其他腳本可以使用以下命令訂閱和取消訂閱此回調事件：

    void OnEnable(){ YourScript.OnSignInSuccess += SignInSuccess; } void OnDisable(){ YourScript.OnSignInSuccess -= SignInSuccess; } private void SignInSuccess(){ Debug.Log("userdatastring: " + YourScript.staticInstance.userDataString); }