Normally, view controllers in a storyboard are instantiated and created automatically in response to actions defined within the storyboard itself. However, you can use a storyboard object to instantiate the initial view controller in a storyboard file or instantiate other view controllers that you want to present programmatically. Below you will find examples of both use cases.
let storyboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle())
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];
Fetch Initial ViewController
let initialScreen = storyboard.instantiateInitialViewController()
UIViewController *initailScreen = [storyboard instantiateInitialViewController];
let viewController = storyboard.instantiateViewControllerWithIdentifier("identifier")
UIViewController *viewController = [storyboard instantiateViewControllerWithIdentifier:@"identifier"];