import UIKit

public extension UITableView {

  public func beginRefreshing() {
    // Make sure that a refresh control to be shown was actually set on the view
    // controller and the it is not already animating. Otherwise there's nothing
    // to refresh.
    guard let refreshControl = refreshControl, !refreshControl.isRefreshing else {
      return
    }

    // Start the refresh animation
    refreshControl.beginRefreshing()

    // Make the refresh control send action to all targets as if a user executed
    // a pull to refresh manually
    refreshControl.sendActions(for: .valueChanged)

    // Apply some offset so that the refresh control can actually be seen
    let contentOffset = CGPoint(x: 0, y: -refreshControl.frame.height)
    setContentOffset(contentOffset, animated: true)
  }

  public func endRefreshing() {
    refreshControl?.endRefreshing()
  }
}

// MARK: - Demo

import PlaygroundSupport

extension UITableViewCell {
  static var identifier: String {
    return String(describing: self.self)
  }
}

class ViewController: UITableViewController {

  override func viewDidLoad() {
    super.viewDidLoad()

    let action = #selector(ViewController.refreshControlDidStart(sender:event:))
    refreshControl = UIRefreshControl()
    refreshControl?.addTarget(self, action: action, for: .valueChanged)

    tableView.register(UITableViewCell.self, forCellReuseIdentifier: UITableViewCell.identifier)
  }

  func refreshControlDidStart(sender: UIRefreshControl?, event: UIEvent?) {
    print(#function)
  }

  override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 100
  }

  override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: UITableViewCell.identifier, for: indexPath)
    cell.textLabel?.text = "SOMETHING"
    return cell
  }
}

let viewController = ViewController()

DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
  viewController.tableView.beginRefreshing()
}

DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
  viewController.tableView.endRefreshing()
}

PlaygroundPage.current.liveView = viewController