How to start a coroutine that will finish after the object is destroyed

Question

I have a simple game in which the player can collect power-ups. Each power-up gives the player a temporary advantage for several seconds. The power-up should disappear immediately after the player collects it.

My current implementation of the power-up logic is:

[SerializeField] float duration;  

private void OnTriggerEnter2D(Collider2D other) {
    if (other.tag == "Player") {
            StartCoroutine(GiveTemporaryPowerup(other.gameObject));
            Destroy(gameObject);
    }
}

private IEnumerator GiveTemporaryPowerup(GameObject gameObject) {
    gameObject.ActivatePowerupFunction();  
    yield return new WaitForSeconds(duration);
    gameObject.DeactivatePowerupFunction();
}

This does not work: the powerup is activated but not deactivated. Deactivation does work when I remove the line "Destroy(gameObject)". However, without this line the player can collect the same powerup several times, which I want to avoid.

I tried to put the coroutine on a component attached to the player object (rather than the power-up object), but this did not solve the problem - deactivate was not called. Here is the updated code on the power-up:

private void OnTriggerEnter2D(Collider2D other) {
    if (other.tag == "Player") {
            var playerComponent = other.gameObject.GetComponent<Player>(); 
            StartCoroutine(playerComponent.GiveTemporaryPowerup(duration));
            Destroy(gameObject);
    }
}

And the code on the Player component:

public IEnumerator GiveTemporaryPowerup(float duration) {
    ActivatePowerupFunction();
    yield return new WaitForSeconds(duration);
    DeactivatePowerupFunction();
}

What is the correct way to implement this?

Answer 1

My mistake was that I thought that StartCoroutine is a global function, and only the coroutine itself should belong to a living object. In fact, it is the other way around. The following code solves the problem:

[SerializeField] float duration;  

private void OnTriggerEnter2D(Collider2D other) {
    if (other.tag == "Player") {
          other.GetComponent<Player>().StartCoroutine(GiveTemporaryPowerup(other.gameObject));
          Destroy(gameObject);
    }
}

private IEnumerator GiveTemporaryPowerup(GameObject gameObject) {
    gameObject.ActivatePowerupFunction();  
    yield return new WaitForSeconds(duration);
    gameObject.DeactivatePowerupFunction();
}