public class UIToggleButton : MonoBehaviour
{
    public UISprite target;
    public string onSprite;
    public string offSprite;

    public bool isOn = false;

    void Start ()
    {
        if (target == null) target = GetComponentInChildren<UISprite>();
    }

    void OnClick ()
    {
        if (target != null)
        {
            isOn = !isOn;
            target.spriteName = isOn ? onSprite : offSprite;
        }
    }

    //This is not a callback, is only used by the WeaponSwitchHud and InputManagerGame components
    public void Switch(bool on)
    {
        isOn = on;
        target.spriteName = isOn ? onSprite : offSprite;
    }
}