Even you can do by giving storyboard identifier "A" to viewController 1 and "B" to viewController 2 and push you controller if using navigation otherwise simply present the viewcontroller.
if subCat[indexPath.row] == "" {
let viewController1 = storyboard.instantiateViewControllerWithIdentifier("A") as! ViewController1
// if navigation controller used.
self.navigationController?.pushViewController(viewController1, animated: true)
// if navigation controller not used.
// self.presentViewController(viewController1, animated: true, completion: nil)
}else{
let viewController2 = storyboard.instantiateViewControllerWithIdentifier("B") as! ViewController2
// if navigation controller used.
self.navigationController?.pushViewController(viewController2, animated: true)
// if navigation controller not used.
// self.presentViewController(viewController2, animated: true, completion: nil)
}