readme.md

Add this to any game object across all scenes

Example usage

public void Start()
{
    EventManager.instance.AddListener("sayHello", OnSayHello);
}

public void OnSayHello()
{
    Debug.Log("Hello!");
}

And then inside of any other script you can trigger the event which will invoke all the registered callbacks

EventManager.instance.Trigger("sayHello");

You can also pass an argument to the callback:

public void Start()
{
    EventManager.instance.AddListener("sayThing", OnSayThing);
}

public void OnSayThing(dynamic thingToSay)
{
    Debug.Log(thingToSay.toString());
}

When you trigger the event, make sure you pass the argument

EventManager.instance.Trigger("sayThing", "Hello world!");

EventManager.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EventManager : MonoBehaviour
{
    static public EventManager instance;
    private Dictionary<string, Action> _eventDelegates;
    private Dictionary<string, Action<dynamic>> _eventDelegatesWithArg;

    public void Awake()
    {
        this._eventDelegates = new Dictionary<string, Action>();
        this._eventDelegatesWithArg = new Dictionary<string, Action<dynamic>>();
        instance = this;
    }

    public void AddListener(string eventName, Action callback)
    {
        if (this._eventDelegates.ContainsKey(eventName))
        {
            this._eventDelegates[eventName] += callback;
        }
        else
        {
            this._eventDelegates.Add(eventName, callback);
        }
    }

    public void AddListener(string eventName, Action<dynamic> callback)
    {
        if (this._eventDelegatesWithArg.ContainsKey(eventName))
        {
            this._eventDelegatesWithArg[eventName] += callback;
        }
        else
        {
            this._eventDelegatesWithArg.Add(eventName, callback);
        }
    }

    public void RemoveListener(string eventName, Action callback = null)
    {
        if (this._eventDelegates.ContainsKey(eventName))
        {
            if (callback != null)
            {
                this._eventDelegates[eventName] -= callback;
            } 
            else
            {
                this._eventDelegates.Remove(eventName);
            }
        }
    }

    public void RemoveListener(string eventName, Action<dynamic> callback = null)
    {
        if (this._eventDelegatesWithArg.ContainsKey(eventName))
        {
            if (callback != null)
            {
                this._eventDelegatesWithArg[eventName] -= callback;
            } 
            else
            {
                this._eventDelegatesWithArg.Remove(eventName);
            }
        }
    }

    public void Trigger(string eventName)
    {
        this.Trigger(eventName, null);
    }

    public void Trigger(string eventName, dynamic arg = null)
    {
        if (this._eventDelegatesWithArg.ContainsKey(eventName))
        {
            this._eventDelegatesWithArg[eventName](arg);
        }

        if (this._eventDelegates.ContainsKey(eventName))
        {
            this._eventDelegates[eventName]();
        }
    }
}