We have a big issue with the current Xcode version (10.2).
There is a BasicViewController class with the following signature:
class Basi
You should attached dataSource and delegate both side using Storyboard and also Class, because once i had the same issue for tableview and it was due to in class i have not done
self.tableView.delegate = self
self.tableView.datasource = self
i think you are not doing like this.
I know that it's not necessary to use both style but some time we need this. have a look on this answer https://stackoverflow.com/a/39443079/3485420