Mute (unity3d)

MuteButton.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

[RequireComponent(typeof(Button))]
public class MuteButton : MonoBehaviour {

    float defaultVolume = 1f;
	void Awake()
    {
        AudioListener.volume = IUMobileSettings.CommonVolume;

        GetComponent<Button>().onClick.SetListener(() =>
        {
            if (AudioListener.volume > 0)
            {
                defaultVolume = AudioListener.volume;
                AudioListener.volume = 0f;
            }
            else
            {
                if(defaultVolume == 0)
                {
                    defaultVolume = 1;
                }
                AudioListener.volume = defaultVolume;
            }

            IUMobileSettings.CommonVolume = AudioListener.volume;
        });
    }
}