How to mark check tableview after search?

Im trying to figure out this code based on others answers.

You will need to add a Bool variable to your object and set it to true or false.

contact.addToGroup = false

Swift 3 example:

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

if let cell = tableView.cellForRow(at: indexPath) {
    let contact = contacts[indexPath.row]

    if (cell.accessoryType == .checkmark) {
        cell.accessoryType = .none
        contact.addToGroup = false
    } else {
        cell.accessoryType = .checkmark
        contact.addToGroup = true
    }

}

tableView.deselectRow(at: indexPath, animated: true)
}

How do i make the contact.addToGroup = false