Check if all tagged GameObject are destroyed

Question

Hello im a total noob so please dont blame me. So, I have this code but I cant find a fitting answer on how to check if everything tagged "Target1" is destroyed. Most of the answers are either overcomplicated or ,and most certainly, im too stupid

public Transform teleportTarget;
public GameObject thePlayer;
public Transform[] spawnLocations;
public GameObject[] whatToSpawnPrefab;
public GameObject[] whatToSpawnClone;

void spawnTargets()
{
    whatToSpawnClone[0] = Instantiate(whatToSpawnPrefab[0], spawnLocations[0].transform.position, Quaternion.Euler(0, 180, 0)) as GameObject;
    whatToSpawnClone[1] = Instantiate(whatToSpawnPrefab[1], spawnLocations[1].transform.position, Quaternion.Euler(0, 180, 0)) as GameObject;
    whatToSpawnClone[2] = Instantiate(whatToSpawnPrefab[2], spawnLocations[2].transform.position, Quaternion.Euler(0, 180, 0)) as GameObject;
    whatToSpawnClone[3] = Instantiate(whatToSpawnPrefab[3], spawnLocations[3].transform.position, Quaternion.Euler(0, 180, 0)) as GameObject;
}

private void TeleportPlayer()
{
    thePlayer.transform.position = teleportTarget.transform.position;
}

Im just looking for a way to check if all GameObjects Tagged "Target1" (in the whole game) are destroyed and then to spawnTargets and TeleportPlayer. Previously I had the bug, that when they respawned it wasnt checking anymore. It has to check all the time.Because else I get stuck, because teleport teleports me all the time. I hope you understand what I mean

I know this is a easy question but im a noob and im sorry for wasting your time, still I hope you can help me.

Answer 1

I want to check if all GameObjects tagged "Target1" have been destroyed, call a function like what you want for example instantiate something and etc...

here is code that you want:

void Update(){
    if(GameObject.FindGameObjectsWithTag("Target1").Length <= 0)
        //call your function to spawn targets and teleports
}

Answer 2

I'd recommend not using tags for this, as searching for matching tags is an unnecessary cost.

Instead, as I described in this related question, I'd recommend creating a MonoBehaviour that marks the objects you want to count, something like this:

public class CountedObject : MonoBehaviour {

    public static int count { get; private set; }

    public static event System.Action AllObjectsDestroyed;

    void Start () {
        // Count every object as it's initialized.
        count++;
    }

    void OnDestroy () {
        // Decrement the count when objects are destroyed,
        // and optionally fire an event when the last one is gone.
        if (--count == 0 && AllObjectsDestroyed != null)
            AllObjectsDestroyed();
    }
}

The static int count variable is shared among all the marked objects. Every time one enters the scene with Start() it increases, and every time one is Destroy()ed, it decreases.

The only time you ever need to check if all objects have been destroyed is when actually processing the destruction - we don't need a script checking for it every frame in Update.

Another script that's interested in getting called when the last object has been destroyed can subscribe to the event, like so:

CountedObject.AllObjectsDestroyed += OnAllDestroyed;

Where void OnAllDestroyed() { ... } is the function you want to call once the last object is gone.

If you want to track/display a count, you can access it with no searching or extra computation or memory allocations, just by asking for:

CountedObject.count

Answer 3

You already seem to keep an array of objects you spawned from the script in whatToSpawnClone. So you can use that array to check how many of them are still alive. You can check if a game object is destroyed by comparing it to null. GameObject has a special overload for the ==-operator which which returns true when you compare a destroyed object to null.

Here is a method you can add to the behaviour which contains the code snippet from the question which checks if all the spawned objects are destroyed.

private bool AtLeastOneCloneAlive() {
     foreach(GameObject o in whatToSpawnClone) {
         if (o != null) return true;
     }
     return false;
}