在其他脚本中引用时，Bool返回不同的值

Question

我正在使用以下脚本检查互联网连接：

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

public class CheckInternets : MonoBehaviour
{
    private string url = "some photo on my google drive";
    private string wwww;

    public static bool InternetON = false; 

    // Start is called before the first frame update
    void Start()
    {        
        StartCoroutine(CheckConnection());
    }

    IEnumerator CheckConnection()
    {
        var www = new WWW(url);

        yield return www;

        if (www.isDone && www.bytesDownloaded > 0)
        {
            InternetON = true;
            Debug.Log("MAIN Script Check :: Online! :)");                        
        }

        if (www.isDone && www.bytesDownloaded == 0)
        {
            InternetON = false;
            Debug.LogWarning("MAIN Script Check :: Offline! :(");
        }
    }
}

在我的（Android）手机上试了这个，连接到移动数据（没有），它运行得很好。

一旦我在其他脚本中引用InternetON bool，就会出现问题，即所述脚本总是将其读作false（如果我将其设置为CheckInternets.cs中的true），那么我的预感是我引用它错了，或者我我没有正确使用bool，但无法弄清楚如何。

其他脚本示例：

void Start()
{        
    if (CheckInternets.InternetON)
    {
        //do some stuff
        Debug.Log("OTHER Script Check :: Online! :)");
    }
    else
    {
        //do some other stuff
        Debug.Log("OTHER Script Check :: Offline! :(");
    }
}

在这种情况下，如果我在线，我的控制台将会显示：

• 其他脚本检查::离线！ :(
• MAIN Script Check ::在线！ :)

如果我处于离线状态，它会为两个人说离线。

有什么建议？干杯!

Answer 1

StartCoroutine(CheckConnection());在coroutine开始Start() ......但是它会在收到MoveNext()电话后收到Update电话后才会被执行

来自Execution Order Documentation：

在Update函数返回后运行正常的协同程序更新。

Update在你的另一个剧本中检查Start中的bool时完成场景的所有Start调用后才被调用CheckConnection()甚至不会执行第一个yield。

---

相反，你必须等到检查完成。

以下是使用IEnumerator Start如何做到这一点的一些方法 Unity允许这样做，以便延迟Start直到某些东西完成...只是你想做的事情：

1. yield CheckConnection 您可以简单地yield return在协程中的任何其他IEnumerator，以便等到另一个完成

   public class CheckInternets : MonoBehaviour
   {
       private static string url = "some photo on my google drive";
       private static string wwww;
   
       public static bool InternetON = false; 
   
       public static IEnumerator CheckConnection()
       {
           var www = new WWW(url);
   
           yield return www;
   
           if (www.isDone && www.bytesDownloaded > 0)
           {
               InternetON = true;
               Debug.Log("MAIN Script Check :: Online! :)");                        
           }
   
           if (www.isDone && www.bytesDownloaded == 0)
           {
               InternetON = false;
               Debug.LogWarning("MAIN Script Check :: Offline! :(");
           }
       }
   }

   和

   public class OtherScript : MonoBehaviour
   {
       IEnumerator Start()
       {
           // starts an internet check and waits until it finished
           yield return CheckInternets.CheckConnection();
   
           if (CheckInternets.InternetON)
           {
               //do some stuff
               Debug.Log("OTHER Script Check :: Online! :)");
           }
           else
           {
               //do some other stuff
               Debug.Log("OTHER Script Check :: Offline! :(");
           }
       }
   }

2. Addistional标志 添加一个标志，例如checkFinished并使用WaitUntil

   public class CheckInternets : MonoBehaviour
   {
       private string url = "some photo on my google drive";
       private wwww;
   
       public static bool InternetON = false;
       public static bool IsFinished = false;
   
       // Start is called before the first frame update
       private void Start()
       {
           StartCoroutine(CheckConnection());
       }
   
       public IEnumerator CheckConnection()
       {
           IsFinished = false;
   
           var www = new WWW(url);
   
           yield return www;
   
           if (www.isDone && www.bytesDownloaded > 0)
           {
               InternetON = true;
               Debug.Log("MAIN Script Check :: Online! :)");
           }
   
           if (www.isDone && www.bytesDownloaded == 0)
           {
               InternetON = false;
               Debug.LogWarning("MAIN Script Check :: Offline! :(");
           }
   
           IsFinished = true;
       }
   }

   并做

   public class OtherScript : MonoBehaviour
   {
       private IEnumerator Start()
       {
           // starts an internet check and waits until it finished
           yield return new WaitUntil(() => CheckInternets.IsFinished);
   
           if (CheckInternets.InternetON)
           {
               //do some stuff
               Debug.Log("OTHER Script Check :: Online! :)");
           }
           else
           {
               //do some other stuff
               Debug.Log("OTHER Script Check :: Offline! :(");
           }
       }
   }

3. 打回来 添加回调Action，这样您就可以在不使用IEnumerator的情况下等待结果

   public class CheckInternets : MonoBehaviour
   {
       private string url = "some photo on my google drive";
       private string wwww;
   
       // now you wouldn't need this anymore and could make it 
       // a local variable in the CheckConnectionRoutine
       public static bool InternetON = false;
   
       public void CheckConnection(Action<bool> callback)
       {
           StartCoroutine(CheckConnectionRoutine(callback));
       }
   
       private IEnumerator CheckConnectionRoutine(Action<bool> callback)
       {
           var www = new WWW(url);
   
           yield return www;
   
           if (www.isDone && www.bytesDownloaded > 0)
           {
               InternetON = true;
               Debug.Log("MAIN Script Check :: Online! :)");
           }
   
           if (www.isDone && www.bytesDownloaded == 0)
           {
               InternetON = false;
               Debug.LogWarning("MAIN Script Check :: Offline! :(");
           }
   
           callback?.Invoke(InternetON);
       }
   }

   并使用方法使用它

   public class OtherScript : MonoBehaviour
   {
       private void Start()
       {
           // somehow get a reference instead of using static
           // that's always the cleaner way
           var check = FindObjectOfType<CheckInternets>();
   
           // starts an internet check
           check?.CheckConnection(OnConnectionCheckFinished);
       }
   
       private void OnConnectionCheckFinished(bool isConnected)
       {
           if (isConnected)
           {
               //do some stuff
               Debug.Log("OTHER Script Check :: Online! :)");
           }
           else
           {
               //do some other stuff
               Debug.Log("OTHER Script Check :: Offline! :(");
           }
       }
   }

   或直接使用lambda表达式

   public class OtherScript : MonoBehaviour
   {
       private void Start()
       {
           // somehow get a reference instead of using static
           // that's always the cleaner way
           var check = FindObjectOfType<CheckInternets>();
   
           // starts an internet check
           check?.CheckConnection((isConnected) =>
           {
               if (isConnected)
               {
                   //do some stuff
                   Debug.Log("OTHER Script Check :: Online! :)");
               }
               else
               {
                   //do some other stuff
                   Debug.Log("OTHER Script Check :: Offline! :(");
               }
           });
       }
   }