I struggled with it myself for some time. This is what I came with in the end :
- setting TMX save mode on CSV
- in Tiled, I used the "tile properties" option (right click on the tilde you want to set), and set "collision" to 1 for example.
- events I used to load the map and set the collisions
- How it renders (i set collisions only on walls)
Here is the .capx
if you want to try. You won't be able to open the tmx file in Tiled though, because of the tileset reference. Open it in notepad, and change the tileset path to yours, it's one of the examples of tiled.