[FIXED] How to use the new Tilemap system with a public gameobject?

Hello Friends, I was very excited when I heard about the new tilemap system.

I am working on a 2d topdown game with a level editor, for this I now want to utilize the new tilemap system.
I have already looked through the documentation and the API reference but couldn't find any information about my following construct.

I have a Controller Object that holds every selectable game item in it's category, this Object is used for the UI and also for the placement system. I want to place my tiles like this:

tilemap.SetTile(positionCursor, selectedTile);

Easy enough, I imported UnityEngine.Tilemaps and added a public variable for both the Tilemap and the Tile. I dragged the Tilemap into it's variable but now I have a problem. I have a RuleTile Asset inside of my Tile Palette and want to reference this now. How would I do that? I tried to find the location Unity saves the tiles but I couldn't find anything. When I try to select a Tile from the UnityUI the list is empty in both tabs.

 

Fixed: I have to use "public TileBase" instead of "public Tile"