select.swift

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
  let selectedCell = tableView.cellForRowAtIndexPath(indexPath)
  tableView.visibleCells.forEach { (cell) -> () in
    cell.accessoryType = .None
  }
  selectedCell?.accessoryType = .Checkmark
  
  tableView.deselectRowAtIndexPath(indexPath, animated: true)
}