UnityEvent.AddListener

Parameters

Description

Adds a runtime listener to the UnityEvent.

This method registers a listener for the UnityEvent at runtime. If the same listener is added multiple times, it is invoked only once per event.

//Attach this script to a GameObject
//This script creates a UnityEvent that calls a method when a key is pressed
//Note that 'q' exits this application.
using UnityEngine;
using UnityEngine.Events;

public class Example : MonoBehaviour
{
    UnityEvent m_MyEvent = new UnityEvent();

    void Start()
    {
        //Add a listener to the new Event. Calls OnKeyPressed method when invoked
        m_MyEvent.AddListener(OnKeyPressed);
    }

    void Update()
    {
        // Press Q to close the Listener
        if (Input.GetKeyDown("q") && m_MyEvent != null)
        {
            Debug.Log("Quitting");
            m_MyEvent.RemoveListener(OnKeyPressed);

            #if UNITY_EDITOR
            UnityEditor.EditorApplication.isPlaying = false;
            #endif

            Application.Quit();
        }

        //Press any other key to begin the action if the Event exists
        if (Input.anyKeyDown && m_MyEvent != null)
        {
            //Begin the action
            m_MyEvent.Invoke();
        }
    }

    void OnKeyPressed()
    {
        //Output message to the console
        Debug.Log("Q key pressed");
    }
}

Additional resources: UnityEventTools.AddPersistentListener.