How to assign a custom function as parameter in Unity UI?

Question

I have a scenario where multiple gameObjects are doing something very similar. onTrigger, a gameObject calls a function in a controller. (The destination function is different for each gameObject, but one gameObject always calls that one function)

This seems like a lot of duplicate code to me and I'd like to abstract the functionality; very similar to how the button OnClick() handles this case:

I naturally thought that was a good place to start and dug around the docs and forums and cobbled together something. Currently, my code is at:

using UnityEngine; 
using UnityEngine.Events;

/**
 * This script takes in a callback function, and a gameObject tag.
 * When OnEnterTrigger2D is executed, calls the call back function if the collision tag matches given tag
 *
 * Use it for reccuring events in multiple gameObjects like spawning obstacles when it hits spawn points,
 * or to call Endgame when player hits obstacles
 */

public class OnTriggerEnterCallFn : MonoBehaviour
{
    public string targetTag;
    public EventTrigger.TriggerEvent callbackFn;

    private void OnTriggerEnter2D(Collider2D other)
    {
        if (other.CompareTag(targetTag))
        {
            callbackFn.Invoke(null);
        }
    }
}

Thought that was all that was reasobable needed, but I seem to be missing something because, in the Unity UI, when I assign the class, my function is not visible at all:

My FlappyBirdObstacleManager has the function definition as public void CreateNewObstacle() and even making that public void CreateNewObstacle(BaseEventData ed) didn't have a positive effect.

What am I missing please?

derHugo · Accepted Answer · 2020-06-17 07:13:59Z

2

You seem to not really require the BaseEventData parameter since you are passing in null anyway. I think you should rather simply use a parameterless UnityEvents instead.

public UnityEvent callbackFn;

answered Jun 17, 2020 at 7:13

derHugo

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1 Comment

LocustHorde Over a year ago

Awesome, that worked, thanks so much, I can't believe I've been searching around about 30 minutes now and didn't look into UnityEvent

Jesper Hustad · Accepted Answer · 2024-05-15 13:05:42Z

0

Example implementation of Unity script with UnityEvent

using UnityEngine;
using UnityEngine.Events; // Make sure to import UnityEvent explicitly

public class DrawingState : MonoBehaviour
{
    [System.Serializable]
    public class CallbackEvent : UnityEvent{}

    public CallbackEvent callbackFn;

    void Start()
    {
        if (callbackFn != null)
        {
            callbackFn.Invoke();
        }
    }
}

answered May 15, 2024 at 13:05

Jesper Hustad

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