CODEWITHSUNDEEP
c#unity-game-engine
yn1043
yn1043

Reputation: 588

How to wait Coroutine callback is executed?

I want to wait StartCoroutine callback is executed. Anyone knows how to do this?

public float getXXX() {
  var result;
  StartCoroutine(YYY((r) => result = r)); // how to wait this?
  return result;
}

private IEnumerator YYY(System.Action<float> callback) {
  LinkedList<float> list = new LinkedList<float>();
  while(timeleft > 0) {
    timeleft -= Time.deltaTime;
    list.add(transform.position.magnitude);
    yield return new WaitForSeconds (WAITSPAN);
  }

  callback(list.max());
  yeild return true;
}

Upvotes: 2

Views: 11454

Answers (3)

Ernie
Ernie

Reputation: 7

I found something you may be able to call the class and use the methods inside this code and modify to use this is very similar to your code but less complex:

using UnityEngine;
using System.Collections;

public class WaitForSecondsExample : MonoBehaviour
{
   void Start()
   {
        StartCoroutine(Example());
   }

    IEnumerator Example()
    {
        print(Time.time);
        yield return new WaitForSeconds(5);
        print(Time.time);
    }
 }

this code was taken from: https://docs.unity3d.com/ScriptReference/WaitForSeconds.html from there examples The 5 is the amount of time it will wait unless you want to do this dynamically based upon something. Depends on what you want to do. However notice how they are calling the method Example() inside the StartCoroutine(Example()) and which will go to the IEnumerator Example() and within there you have WaitForSeconds(5); this will make the StartCoroutine wait for 5 seconds. This can be hardcoded or made to wait dynamically by calling another method within that class from within IEnumerator Example() this is just one of many ways you can attack this. Again depends on what you want to do. Actually, you might even be better off making this into a method that passes a value in to the method each time something like 

    IEnumerator Example(float flSeconds)
    {
        print(Time.time);
        yield return new WaitForSeconds(flSeconds);
        print(Time.time);
    }

this way you can pass what is in your LinkedList list = new LinkedList(); Every time

Upvotes: 0

Programmer
Programmer

Reputation: 125245

You can't and shouldn't try to wait or yield for a coroutine function to return from non coroutine function (getXXX function). It will block in that non coroutine function until this function returns preventing other Unity scripts to run.

To wait for a coroutine function(YYY) in the getXXX function, you must also make the function you are making the call and waiting from in a coroutine function. In this case this is theYYY function, so that should be a corutine function too then you can yield it:

public IEnumerator getXXX()
{
    float result = 0f;
    yield return StartCoroutine(YYY((r) => result = r)); // how to wait this?

    //Use the result variable
    Debug.Log(result);
}

OR

If you don't want to make the getXXX function a a coroutine function then don't try to wait there. You can still use the result from the YYY coroutine function but don't try to return the result. Just use it to do whatever you want to do in that function:

public void doSomethingXXX()
{
    StartCoroutine(YYY((result) =>
    {
        //Do something with the result variable
        Debug.Log(result);

    }));
}

The idea of using coroutine is to be able to do something over multiple frames. The void function will just do that in one frame. You can't yield/wait in a void or non IEnumerator/coroutine functio.

Upvotes: 5

Behnam Rasooli
Behnam Rasooli

Reputation: 722

You can only wait inside a coroutine. To do this, your getXXX() method should also be a coroutine. Something like this:

public float someOtherMethod()
{
    float result;
    StartCoroutine(getXXX(out result));
    return result;
}

IEnumerator getXXX(out float result)
{
    //more code here...
    yield return StartCoroutine(YYY((r) => result = r));
    //more code here...
}

IEnumerator YYY(System.Action<float> callback)
{
    //your logic here...
}

Upvotes: 2

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