Stop coroutine including nested couroutines

Unity Engine
1

StopCoroutine doesn’t seem to stop nested coroutines. For example:

using UnityEngine;
using System.Collections;

public class NewBehaviourScript : MonoBehaviour
{
    private void Start()
    {
        StartCoroutine("Parent");
    }
  
    private void Update()
    {
        if (Input.GetKeyUp(KeyCode.S))
        {
            Debug.Log(Time.frameCount + " stop");

            StopCoroutine("Parent");
        }
    }

    private IEnumerator Parent()
    {
        while (true)
        {
            yield return StartCoroutine("Child");
        }
    }

    private IEnumerator Child()
    {
        yield return new WaitForSeconds(1);

        Debug.Log(Time.frameCount + " test");
    }
}

Since the Child coroutine was started from Parent I would expect that stopping Parent would also stop Child. However, it seems that Child continues to run until it’s done.

Is there any (nice) way to stop nested coroutines?

2

StopAllCoroutines?

3

Unity - Scripting API: MonoBehaviour.StopAllCoroutines :slight_smile:

4

StopAllCoroutines would work in this example but there are situations where I’m running multiple coroutines on an object and I don’t want to stop all of them. I want to stop a specific coroutine and any nested coroutines it started.

I’m pretty sure the answer is that it can’t be done (at least not with any built-in APIs). Maybe this is more of a feature request. :slight_smile:

5

Necro, but for anyone looking for that:
You can save IEnumerators and stop them manually like so:

        IEnumerator curCo = null;

        public void FadeOutAndDisable()
        {
            if (!gameObject.activeInHierarchy) return; // already disabled

            if (curCo != null)
            {
                StopCoroutine(curCo);
            }
            curCo = CoFadeOut();
            StartCoroutine(curCo);

        }
6

It depends on your setup. You should maintain the flow if your script. If you got a coroutine starting, let it create a list to store all the others. Thats what a built in thing would do. But as it is content/script architecture related, it is not :wink:

7

What if you maintain a reference to your coroutines and manage them with the hierarchy you want?

8

Unity handles this for you from a while back if you just yield the child IEnumerator (do not call Start corotine just yield the enumerator)

3 Likes
9

@AndersMalmgren
How does this work?
Will it actually start the child Coroutine?
Could you give an example?

10

Yes unity will do an internal StartCorotuine

11

@AndersMalmgren Did you find it anywhere in the docs? If so provide me with some links, please :slight_smile:

12

No, I just tried it and it worked :smile:

2 Likes