Scroll the header view along with the UITableView

UIKit_ScrollableTableHeaderView.swift

extension ViewController: UIScrollViewDelegate {

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        guard let tableView = scrollView as? UITableView,
            let visible = tableView.indexPathsForVisibleRows,
            let first = visible.first else {
            return
        }

        let headerHeight = tableView.rectForHeader(inSection: first.section).size.height
        let offset =  max(min(0, -tableView.contentOffset.y), -headerHeight)
        self.tblView.contentInset = UIEdgeInsets(top: offset, left: 0, bottom: -offset, right: 0)
   }
}