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