another noob question: callback functions? SOLVED

Unity Engine
1

hi!

I want to create a timer function in c# to do some timing stuff :slight_smile: To do that I would like to create a method like this:

void SetTimer(float TimeToWait, Object(??) CallbackFunction)

and then use it like so:

SetTimer(3.0f, TheMethodThatNeedsToBeCalledWhenTheTimerIsFinished);

void TheMethodThatNeedsToBeCalledWhenTheTimerIsFinished()
{
   // do some stuff
}

Is this possible and if so, how do I do it? I read some stuff about delegates but I have to admit that I don’t really understood that…

2

Look into coroutines, they’ll be a big help here. For example, start here with StartCoroutine. :slight_smile:

3

I have it working now, here’s what I did:

I created a TimerFunctionsClass:

using UnityEngine;


public class TimerFunctionsClass: MonoBehaviour
{
	public delegate void OnTimerEvent();

	private OnTimerEvent CallBackFunction;			// the function that is called when the time is up
	private float OriginalTimeInterval;					// used for resetting
	private float TimeLeft;									// used for counting down
	private bool Active = false;
	

	// setup the timer: how long should the timer wait and which function should it call when the event is triggered
	public void SetTimer(float TimeInterval, OnTimerEvent NewCallBackFunction)
	{	
		TimeLeft = TimeInterval;
		CallBackFunction = NewCallBackFunction;		
	}
	

	// actually start the timer:
	public void StartTimer()
	{		
		Active = true;
	}
   

	// I'm not using this, but whatever:
	public void StopTimer()
	{
		Active = false;
	}
	
	
	// ohwell
	public void ResetTimer()
	{
		TimeLeft = OriginalTimeInterval;
	}

	
public void DestroyTimer()
	{
		Destroy(this);
	}


	// TimeLeft is decreased by Time.deltaTime every tick, if it hits 0 then the CallBackFunction is called
	void Update()
	{		
		if (Active == true)
		{	
			TimeLeft -= Time.deltaTime;
			if (TimeLeft <= 0)
			{
				CallBackFunction();
				StopTimer();	
DestroyTimer();
			
			}
		}
	}
}

And here is how I use the timer in my game code:

void DoSomething()
	{
		Debug.Log("do something!");
		
	}

void Start()
{
TimerFunctionsClass MyTimer;
				
		gameObject.AddComponent("TimerFunctionsClass");
		MyTimer = (TimerFunctionsClass)gameObject.GetComponent(typeof(TimerFunctionsClass));
		MyTimer.SetTimer(10.0f, DoSomething);
		MyTimer.StartTimer();
}

it’s probably not-so-good-code but it works for me :slight_smile:

4

Thats actually bad code, not “not so good” I fear

A simple coroutine and yield return WaitForSeconds(yourWaitTime); would do the same thing

pause is not needed as setting the timescale to 0 will pause coroutines too and ending them is possible through StopCoroutine

5

I tried using

yield return WaitForSeconds(yourWaitTime);

but I could not get it to work, nomatter what I tried the error messages just kept becoming more and more exotic.

Can you give me example code of a “good version” of this class? The code above works as intended but I suppose using WaitForSeconds would be more efficient.

By the way, the delegate stuff is correct right?

6

check out the script docs on StartCoroutine and WaitForSeconds

they will give you an idea on coroutines.