Resources.Load

素材は、Resourcesにまとめて、スクリプトから名前を指定して呼び出す。

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

public class ResourceText : MonoBehaviour {

	private GameObject ImageObj;
	private const string ImageObjPath = "Image";

	private void Awake (){
		ImageObj = transform.FindChild (ImageObjPath).gameObject;

	}
	private void Start () {
		Debug.Log (ImageObj);
		ImageObj.GetComponent<Image> ().sprite = Resources.Load<Sprite> ("Image/gui_button_3");
	}
	void Update () {
	
	}
}