Thanks @nargarus. I'll give it a try asap.

@Polyphonic datasource isn't a computed property. As you can see the =, so it's only called once. I don't really get why having custom section and row type should solve the problem. It comes to the same than having \.self because the Int and the String are unique in my example. I tried your solution anyway, but it's the same result. I wonder if under the hood List just works like UITableView, which would mean that it will reuse each row when it can and call onAppear only once.

@nargarus, it's working, thanks for the tip!