试试这个

 func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let height = scrollView.frame.size.height
    let contentYoffset = scrollView.contentOffset.y
    let distanceFromBottom = scrollView.contentSize.height - contentYoffset
    if distanceFromBottom < height {
        print(" you reached end of the table")
    }
}

或者你可以这样找到

if tableView.contentOffset.y >= (tableView.contentSize.height - tableView.frame.size.height) {    
    //you reached end of the table
}