DelegatesExample

using UnityEngine;
using System.Collections;

public class EventManager : MonoBehaviour {
    public delegate void PowerUpHandler (bool isPoweredUp);
    public static event PowerUpHandler onPoweredUp;

    public void PowerUp () {
        if (onPoweredUp != null)
            onPoweredUp (true);
    }

    public void PowerOff () {
        if (onPoweredUp != null)
            onPoweredUp (false);
    }
}

public class EventListener : MonoBehaviour {
    void OnEnable () {
        EventManager.onPoweredUp += OnPoweredChange;
    }

    void OnDisable () {
        EventManager.onPoweredUp -= OnPoweredChange;
    }

    void OnPoweredChange (bool isPoweredUp){
        print (isPoweredUp? "Powered" : "Unpowered");
    }
}