I have updated my code to swift 3.0 and get a warning on the following line:
func tableView(_ tableView: UITableView, cellForRowAtIndexPath indexPath: IndexP
I had a similar problem, and found that if you remove the space between the underscore before tableView, from this
func tableView(_ tableView: ...
to this
func tableView(_tableView: ...
strangely the warning goes away...