Version: 2017.2
public GUIStyle FindStyle (string styleName);

説明

GUIStyle 名で GUIStyle オブジェクトを検索します。ない場合は null を返します

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public string aStyleName = "A Style I have"; void OnGUI() { if (GUI.skin.FindStyle(aStyleName) == null) Debug.LogWarning("No style named \"" + aStyleName + "\" could be found"); } }