Yes, it is working. Thx a lot.

Thx for that. I didn't know the trick with Dictionary by grouping, very useful ! If I understand well, we can group by a parameter and then another, right ? So in my case, I'd like to have [artist[album[title, title, title, title]][album[title, title, title]][album[title, title, title, title, title]][album[title]]] to have a tree. So I need to do multiple Dictionary with maps in the for() or can I group directly in one dictionary ? Thx.

I tried : func searchFieldDidEndSearching(_ sender: NSSearchField) {         _filterTracks(str: "") } And same result >>> the NSTableView is empty now... Logical because it's looking for items which contains an empty string and there is not... Or is there a reloadData() or something to call is this case ?