calcImageRatio.swift

extension UIImage {
  func calcImageRatio() -> CGFloat {
  let imageRatio = CGFloat(self.size.width / self.size.height)
  return imageRatio
  }
}

override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
  let currentImage = images[indexPath.row]
  let imageRatio = currentImage.calcImageRatio()
  return tableView.frame.width / imageRatio
}