CoreData entity has no subscript members

Students is a CoreData entity. The issue is that the last line gives an error "Students[row] has no subscript members" Please any advice?

let moContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext

var students_s = [Students]()

override func viewDidLoad() {
    super.viewDidLoad()

override func viewDidAppear(animated: Bool) {

           let request = NSFetchRequest(entityName: "Students")

    do {
        try students_s = moContext.executeFetchRequest(request) as! [Students]
        print("Saved")
        self.tableView.reloadData()


    } catch {
        print("Failed")
    }

}

    let student = students_s[indexPath.row]
    cell.textLabel?.text = student.first_name
    cell.detailTextLabel?.text = student.last_name

    return cell
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    if (segue.identifier == "editStudent")

            {
                guard let v = segue.destinationViewController as? ViewController else {
                    return
                }

                guard let indexPath = self.tableView.indexPathForSelectedRow else {

                    return
                }

                let row = indexPath.row
                v.students_s = Students[row!]





}