Unexpectedly found nil, when I convert to storyboard for chat application

func showChatControllerForUser() {
    let chatLogController = ChatLogController(collectionViewLayout: UICollectionViewFlowLayout())
    chatLogController.user = user



    var storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    var vc: UINavigationController = storyboard.instantiateViewControllerWithIdentifier("ChatLog") as! UINavigationController


    presentViewController(vc, animated: true, completion: nil)
}

I am converting my chat controller to storyboard and this is my code. user information is store inside chatLogController.user.

However now that i'm using storyboard, I keep getting nil for it.

I know i'm writting this code wrong, and would really appreciate your help.