need to make a timer that works with a collider

Questions & Answers
1

i have an object that when it collides with an enemy after 3 seconds it destroys the enemy. the problem is that the collider only works inside OnTriggerStay (as far as i know) but the problem is that OnTriggerStay all happens within the span of 1 frame and I’m trying to use real time. this is my prototype code trying to make the idea work:
public class DestroyGhost : MonoBehaviour {
private float timer = 0;
public GameObject enemy;

void OnTriggerStay(Collider col)  {
    if (col.gameObject.tag == "Enemy") {
        for (float timer = 0; timer < 3; timer += Time.deltaTime) {
            Debug.Log(timer);
        }
        Destroy(enemy);
        
    }
    if (col.gameObject.tag != "Enemy") {
        timer = 0;
    }
}
3

If you want to destroy the enemy 3 seconds after the beginning of the collision, you can use:

void OnTriggerEnter(Collider col) {
     if (col.gameObject.tag == "Enemy") {
         Destroy (enemy, 3);
     }

If you want to destroy the enemy after it collided during 3 seconds, you can use something like that :

float timer = 0;

void OnTriggerStay(Collider col)  {
     if (col.gameObject.tag == "Enemy") {
          timer += Time.deltaTime);
         }  
     }

void OnTriggerExit(Collider col) {
     if (col.gameObject.tag == "Enemy") {
         timer = 0;
     }
 }

void Update () {
    if (timer > 3) { Destroy(enemy) }
}
2

Try this:

`

void OnTriggerEnter(Collider col) {
	if (col.gameObject.tag == "Enemy")
		Invoke("destroyEnemy", 3.0f);
}

private void destroyEnemy() {
	// do something before destroy
	Destroy(enemy);
}

or this:

void OnTriggerEnter(Collider col) {
	if (col.gameObject.tag == "Enemy")
		Destroy(enemy, 3.0f);
}

`