override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if let cell = tableView.cellForRow(at: indexPath as IndexPath) {
if cell.accessoryType == .checkmark {
cell.accessoryType = .none
} else {
cell.accessoryType = .checkmark
}
}
tableView.deselectRow(at: indexPath, animated: true)
}