Segue not getting selected row number

The best way to do this kind of thing is not to use the delegate.

Updated Swift 4+

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let selectedIndex = tableView.indexPath(for: sender as! UITableViewCell)
    // Do your stuff with selectedIndex.row as the index
}

Original Answer

override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
    let selectedIndex = self.tableView.indexPathForCell(sender as UITableViewCell)
    // Do your stuff with selectedIndex.row as the index
}