문제해결)Unity)UnityException: ~ can only be called from the main thread.Constructors and field initializers will be executed from the loading thread when loading a scene.Don't use this function in the constructor or field initializers, inst..

~ can only be called from the main thread.Constructors and field initializers will be executed from the loading thread when loading a scene.Don't use this function in the constructor or field initializers, inst..

 

해당이슈는 Unity에서 Main Thread가 아닌곳에서 UnityEngine의 기능을 호출할때 발생하는 이슈이다.

 

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여러상황에서 발생이 가능한데. 외부 라이브러리 <> Unity 사이에서 발생하는 경우가 종종있다.

Unity 에서 Main Thread를 보장하는곳에서 호출하려면 간단하게 Mono Update에서 호출하거나 Corotine을 통해서 호출하는 방법이 있다.

 

참고코드

<MobileAdsEventExecutor.cs>

// Copyright (C) 2018 Google, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

namespace GoogleMobileAds.Common
{
    public class MobileAdsEventExecutor : MonoBehaviour
    {
        public static MobileAdsEventExecutor instance = null;

        private static List<Action> adEventsQueue = new List<Action>();

        private volatile static bool adEventsQueueEmpty = true;

        public static void Initialize()
        {
            if (IsActive())
            {
                return;
            }

            // Add an invisible game object to the scene
            GameObject obj = new GameObject("MobileAdsMainThreadExecuter");
            obj.hideFlags = HideFlags.HideAndDontSave;
            DontDestroyOnLoad(obj);
            instance = obj.AddComponent<MobileAdsEventExecutor>();
        }

        public static bool IsActive()
        {
            return instance != null;
        }

        public void Awake()
        {
            DontDestroyOnLoad(gameObject);
        }

        public static void ExecuteInUpdate(Action action)
        {
            lock (adEventsQueue)
            {
                adEventsQueue.Add(action);
                adEventsQueueEmpty = false;
            }
        }

        public static void InvokeInUpdate(UnityEvent eventParam)
        {
          ExecuteInUpdate(() =>
          {
              eventParam.Invoke();
          });
        }

        public void Update()
        {
            if (adEventsQueueEmpty)
            {
                return;
            }

            List<Action> stagedAdEventsQueue = new List<Action>();

            lock (adEventsQueue)
            {
                stagedAdEventsQueue.AddRange(adEventsQueue);
                adEventsQueue.Clear();
                adEventsQueueEmpty = true;
            }

            foreach (Action stagedEvent in stagedAdEventsQueue)
            {
                if (stagedEvent.Target != null)
                {
                    stagedEvent.Invoke();
                }
            }
        }

        public void OnDisable()
        {
            instance = null;
        }
    }
}

 

 

https://assetstore.unity.com/packages/tools/utilities/thread-dispatcher-202421

Thread Dispatcher | 유틸리티 도구 | Unity Asset Store

https://github.com/googleads/googleads-mobile-unity/blob/main/source/plugin/Assets/GoogleMobileAds/Common/MobileAdsEventExecutor.cs

GitHub - googleads/googleads-mobile-unity: Official Unity Plugin for the Google Mobile Ads SDK

 

 

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