Hi,

We have an event system that spawns Goblins via a GoblinManager like this:

using UnityEngine;
using System.Collections;

public class EventGoblinWave : EventT {

    private GoblinManager mManager;

    public EventGoblinWave(GoblinManager aManager) : base("Goblin Wave")
    {   
       mManager = aManager;
       //spawn 3 goblins here
       for (int i = 0; i < 3; i++)
       {
         mManager.SpawnGoblin(new Vector3(5, 47, -7));
       }
    }

    public void Update()
    {
       base.Update();
    }
}

now we want to spawn some from an object that is on the scene via the same GoblinManager and we do it like this:

using UnityEngine;
using System.Collections;
public class GoblinHut : MonoBehaviour
{
    public int HitPoints;

    private GoblinManager mManager;
    private MainGameLoop mMainGameLoop;
    private float mSpawnTimer;

    // Use this for initialization
    void Start () {
       HitPoints = 200;
       mSpawnTimer = -1;

       mMainGameLoop = GameObject.Find("MainGameLoop").GetComponent("MainGameLoop") as MainGameLoop;
       mManager = mMainGameLoop.GetGoblinManager();
    }

    // Update is called once per frame
    void Update ()
    {
       if (mManager == null)
       {
         mManager = mMainGameLoop.GetGoblinManager();
       }

       if (mSpawnTimer >= 2)
       {
         mManager.SpawnGoblin(transform.position);
         mSpawnTimer = 0;
       }
       else
       {
         mSpawnTimer += Time.deltaTime;
       }
    }

    public void GetHit(int aHitPointLoss)
    {
       if (HitPoints > 0)
       {
         HitPoints -= aHitPointLoss;
       }
    }
}

when we spawn the object from the GoblinHut via the GoblinManager we get a NullReferenceException when the GoblinManager check if the goblin spawned is dead. It seems it's because the Start() has not been called when called from the GoblinHut. The thing I don't understand is that Start() is called when the event spawn them.

Here is the GoblinManager class:

using UnityEngine;
using System.Collections;

public class GoblinManager : MonoBehaviour {

    private ArrayList mGoblins;
    public GameObject GoblinPrefab;
    private Object mMainLoop;

    public void SetMainLoop(Object aMainLoop)
    {
       mMainLoop = aMainLoop;
    }

    // Use this for initialization
    void Start () 
    {
       mGoblins = new ArrayList();
    }

    public void SpawnGoblin(Vector3 aPos)
    {
       GameObject newGoblin = Instantiate(GoblinPrefab, aPos, Quaternion.identity) as GameObject;
       newGoblin.active = true;
       if (newGoblin != null)
       {
         mGoblins.Add(newGoblin);
       }
    }

    // Update is called once per frame
    public void Update () 
    {
       for (int i = 0; i < mGoblins.Count; i++)
       {
         GameObject obj = (GameObject)mGoblins[i];
         if (obj.active)
         {
          EnemyGoblin goblin = obj.GetComponent<EnemyGoblin>();
          if (goblin != null)
          {
              if (goblin.IsDead())
              {
                 Destroy((Object)mGoblins[i]);
                 mGoblins.RemoveAt(i);
                 break;
              }
          }
         }
       }
    }
}

Thanks for you help