In MainViewController TableView is nil

I am new on Swift and iOS, i tried to integrate this SlideMenuController to my project but i take
"Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value" error while executing on MainViewController's viewDidLoad() class and also i couldn't get where the @IBOutlet weak var tableView: UITableView! value set in the code. As far as i understand from web it allows us to use weakly defined variable, which is inside of the class on storyboard, in viewDidLoad(). However, i can't access it although i create a UITableView in the UIViewController(MainViewController) in storyboard . Can someone please explain me ?

Note: I have also same issue in LeftViewController and RightViewController..

Start with MainViewController.viewDidLoad() and the storyboard scenes for MainViewController, LeftViewController, and RightViewController; verify how each @IBOutlet tableView is connected. Done means the three controllers load without the nil-unwrapping crash and the relevant storyboard setup is explained.

Written by the indexing model from the issue text.