SceneField.cs

// Taken from: https://discussions.unity.com/t/inspector-field-for-scene-asset/40763

using UnityEngine;

#if UNITY_EDITOR
using UnityEditor;
#endif

[System.Serializable]
public class SceneField
{
	[SerializeField]
	private Object m_SceneAsset;

	[SerializeField]
	private string m_SceneName = "";
	public string SceneName
	{
		get { return m_SceneName; }
	}

	// makes it work with the existing Unity methods (LoadLevel/LoadScene)
	public static implicit operator string( SceneField sceneField )
	{
		return sceneField.SceneName;
	}
}

#if UNITY_EDITOR
[CustomPropertyDrawer(typeof(SceneField))]
public class SceneFieldPropertyDrawer : PropertyDrawer 
{
	public override void OnGUI(Rect _position, SerializedProperty _property, GUIContent _label)
	{
		EditorGUI.BeginProperty(_position, GUIContent.none, _property);
		SerializedProperty sceneAsset = _property.FindPropertyRelative("m_SceneAsset");
		SerializedProperty sceneName = _property.FindPropertyRelative("m_SceneName");
		_position = EditorGUI.PrefixLabel(_position, GUIUtility.GetControlID(FocusType.Passive), _label);
		if (sceneAsset != null)
		{
			sceneAsset.objectReferenceValue = EditorGUI.ObjectField(_position, sceneAsset.objectReferenceValue, typeof(SceneAsset), false); 

			if( sceneAsset.objectReferenceValue != null )
			{
				sceneName.stringValue = (sceneAsset.objectReferenceValue as SceneAsset).name;
			}
		}
		EditorGUI.EndProperty( );
	}
}
#endif