Stickyheaderview.swift

 private let kTableHeaderHeight: CGFloat = 300
  var headerView: UIView!
  
  override func viewDidLoad() {
    super.viewDidLoad()
    
    headerView = tableView.tableHeaderView
    tableView.tableHeaderView = nil
    
    tableView.addSubview(headerView)
    
    tableView.contentInset = UIEdgeInsets(top: kTableHeaderHeight, left: 0, bottom: 0, right: 0)
    tableView.contentOffset = CGPoint(x: 0, y: -kTableHeaderHeight)
    
  }
  
  func updateHeaderView(){
    var headerRect = CGRect(x: 0, y: -kTableHeaderHeight, width: tableView.bounds.width, height: kTableHeaderHeight)
    if tableView.contentOffset.y < -kTableHeaderHeight{
      headerRect.origin.y = tableView.contentOffset.y
      headerRect.size.height = -tableView.contentOffset.y
    }
  }
  
  override func scrollViewDidScroll(_ scrollView: UIScrollView) {
    updateHeaderView()
  }