Coroutine WaitForSeconds does not work after destroying an object

Hello,

I am working on a simple Space Invaders clone and when the player gets hit by enemy bullet, I want to wait 3 seconds and then load the Menu scene. I am using coroutine for this and this is how my script for an enemyBullet looks like. The problem is that when the player collides with a bullet, the SceneManager does not wait 3 seconds but loads a menu scene immediately. Why is that? Thank you very much

Code (CSharp):

1.   private void OnTriggerEnter2D(Collider2D collision)
2.  
3. IEnumerator restartWaiter()
4.     {
5.  
6.         yield return new WaitForSeconds(3.0f);
7.  
8.     }
9.    
10.  
11. {
12.         if (collision.gameObject.tag == "Player")
13.         {
14.  
15.             Destroy(this.gameObject);
16.             Destroy(collision.gameObject);
17.             restartLevel();
18.         }
19.  
20. private void restartLevel()
21.     {
22.         StartCoroutine(restartWaiter());
23.         SceneManager.LoadScene("Menu");
24.     }
25.  
26.  
27.  }

 

It's because a Coroutine belongs to the game object that starts it. If you destroy the object, you destroy the Coroutine.

This really isn't something your bullets should be doing anyway. Make a GameManager, and have bullets (or the things they hit) inform the GameManager of what's happened, and let that do stuff like load the next scene. Keep all your game-manager-y logic in one place, not spread out among a bunch of unrelated scripts.

 

Thank you, that makes sense now

 

So I tried to do as you said, and still no luck. The SceneManager loads the level instantly and still does not wait 3 seconds before doing so. This is my GameManager script:

Code (CSharp):

1.  IEnumerator restartWaiter()
2.     {
3.         yield return new WaitForSeconds(3.0f);
4.     }
5.  
6. public void restartLevel()
7.     {
8.         StartCoroutine(restartWaiter());
9.         SceneManager.LoadScene("Menu");
10. }

And this is a part of my enemyBullet script:

Code (CSharp):

1. public class enemyBullet : MonoBehaviour
2. {
3.     public GameManager gameManager;
4.  
5.     // Start is called before the first frame update
6.     void Start()
7.     {
8.         gameManager = FindObjectOfType<GameManager>();
9.     }
10.  
11.     private void OnTriggerEnter2D(Collider2D collision)
12.     {
13.         if (collision.gameObject.tag == "Player")
14.         {
15.  
16.             Destroy(this.gameObject);
17.             Destroy(collision.gameObject);
18.  
19.             gameManager.restartLevel();
20.         }
21.  
22.     }
23.  
24.  
25. }
26.  
27.  

 

Code (csharp):

1.  
2.        StartCoroutine(restartWaiter());
3.  

This line starts a coroutine, which will sort of spawn off and do its own thing, while the code that started it continues right on to the next line:

Code (csharp):

1.  
2.         SceneManager.LoadScene("Menu");
3.  

...which immediately loads the Menu scene. Indeed, since your restartWaiter() method does nothing but wait, it is a useless method that could never have any effect at all.

If you don't understand Coroutines (and in most cases, even when you do), then I don't recommend using them. You'd probably be better off using Invoke with the delay (time) parameter, which is much easier to understand.

But if you feel you must use a Coroutine, then your coroutine method needs to both wait and do the LoadScene. And the code that starts the coroutine should start it, and do nothing else.

 

Thank you, I understand and it works perfectly now. Also I will take a look at invoke.

 

solved my issue with non-working coroutine involving an object that called the coroutine after being deleted.

I used invoke in the player class instead of my other object class (the object that was getting destroyed)
Thanks