Save and restore objects to the editor prefs

EditorPrefsObjectHelper.cs

using UnityEditor;
using UnityEngine;

namespace Adnc.EditorHelpers {
    public static class EditorPrefsObjectHelper {
        /// <summary>
        /// Save the object to the editor prefs. Only persists for the current editor session
        /// </summary>
        /// <param name="key"></param>
        /// <param name="obj"></param>
        public static void SaveObject (string key, Object obj) {
            var val = obj == null ? -1 : obj.GetInstanceID();
            EditorPrefs.SetInt(key, val);
        }

        /// <summary>
        /// Restore the object from editor prefs
        /// </summary>
        /// <param name="key"></param>
        /// <param name="nullValue"></param>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static T RestoreObject<T> (string key, T nullValue = null) where T : Object {
            var id = EditorPrefs.GetInt(key, -1);
            var result = EditorUtility.InstanceIDToObject(id);

            if (result == null) {
                return nullValue;
            }

            return result as T;
        }
    }
}