Storyboard

Initialize

//Swift    
let storyboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle()) 

//Objective-c
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];

Fetch Initial ViewController

//Swift
let initialScreen = storyboard.instantiateInitialViewController()

//Objective-c
UIViewController *initailScreen = [storyboard instantiateInitialViewController];

Fetch ViewController

//Swift    
let viewController = storyboard.instantiateViewControllerWithIdentifier("identifier")

//Objective-c
UIViewController *viewController = [storyboard instantiateViewControllerWithIdentifier:@"identifier"];