How does the RuleTile from Unitys 2D-extras work?

I have watched this tutorial where they are using the RuleTile from the "2D-extras" repository (link).

To learn how this stuff works, I started to implement this RuleTile on my own. Everything is fine until I close the Unity Editor and reopen it. All the changes I had made on the RuleTile were gone.

After spending some hours searching on the internet I got some of the features to work by using SerializedProperties in the custom editor instead of accessing the properties directly.

• Does the RuleTile/RuleTileEditor work with the current version of unity (2017.4)?

• Do I have to mess around with the SerializedProperty/SerializedObejct stuff to get this running?

• Is there any other solution to place tiles automatically in a similar way?

Some Code Fragments from the 2D Extra RuleTile

 [Serializable]
 [CreateAssetMenu]
 public class RuleTile : TileBase
 {
     [Serializable]
     public class TilingRule
     {
         ...
     }
     
     public List<TilingRule> m_TilingRules;
     
     public Sprite m_DefaultSprite;
     public Tile.ColliderType m_DefaultColliderType = Tile.ColliderType.Sprite;
     
     ...
 }

 [CustomEditor(typeof(RuleTile))]
 [CanEditMultipleObjects]
 internal class RuleTileEditor : Editor
 {
     private ReorderableList m_ReorderableList;

     public RuleTile tile { get { return (target as RuleTile); } }

     public void OnEnable()
     {
         if (tile.m_TilingRules == null)
             tile.m_TilingRules = new List<RuleTile.TilingRule>();

         m_ReorderableList = new ReorderableList(tile.m_TilingRules, typeof(RuleTile.TilingRule), true, true, true, true);
         ...
     }
     
     public override void OnInspectorGUI()
     {
         tile.m_DefaultSprite = EditorGUILayout.ObjectField("Default Sprite", tile.m_DefaultSprite, typeof(Sprite), false) as Sprite;
         tile.m_DefaultColliderType = (Tile.ColliderType)EditorGUILayout.EnumPopup("Default Collider", tile.m_DefaultColliderType);
         EditorGUILayout.Space();

         if (m_ReorderableList != null && tile.m_TilingRules != null)
             m_ReorderableList.DoLayoutList();
     }
 }

My modifications

 [Serializable]
 public class RuleTile : TileBase {
     [SerializeField]
     private List<TilingRule> tilingRules;

     [SerializeField]
     private Sprite defaultSprite;

     [SerializeField]
     private Tile.ColliderType defaultCollider;
 }
 
 [CustomEditor(typeof(RuleTile))]
 public class RuleTileEditor : Editor {
     protected RuleTile tile {get { return serializedObject.targetObject as RuleTile; }}

     //Serialization
     private SerializedProperty defaultColliderProperty;
     
     public void OnEnable(){
         //Properties
         defaultColliderProperty = serializedObject.FindProperty("defaultCollider");
         
         ...
     }
     
     public override void OnInspectorGUI ()
     {
         serializedObject.Update ();

         //deserialize values
         Tile.ColliderType collider = (Tile.ColliderType)defaultColliderProperty.enumValueIndex;

         //Layout GUI
         collider = (Tile.ColliderType) EditorGUILayout.EnumPopup (colliderTypeLabel, collider);

         //serialize values
         defaultColliderProperty.enumValueIndex = (int)collider;

         serializedObject.ApplyModifiedProperties ();
     }
 }