I presented a login screen as follows modally. Correct me if I am not right.
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@\"Main\" bundle:nil]
Just set the modalTransitionStyle property for the viewController. (Documentation)
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
UIViewController *ivc = [storyboard instantiateViewControllerWithIdentifier:@"login"];
[ivc setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];
[self presentViewController:ivc animated:YES completion:nil];
In Swift:
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier: "login")
viewController.modalTransitionStyle = .crossDissolve
present(viewController, animated: true, completion: nil)