Transitioning from swift file to StoryBoard

Class UIStoryboard
Use the UIStoryboard class.There are only three items, including the initiators, so there is no doubt about it.
After pressing the button (goNext(_:)), instantiate the "Next.storyboard" with the UINavigationController as the Initial View Controller and include the code you want to transition to as a sample.

@IBAction funcgoNext(_sender:Any){
    let storyboard = UIStoryboard (name: "Next", bundle:nil)
    iflet navigationController=storyboard.instantiateInitialViewController()as?UINavigationController{
        present(navigationController, animated:true, completion:nil)
    }
}

Be careful not to forget to specify the Initial View Controller when you create a new Storyboard.You must specify a View Controller from which to start the Storyboard, which is called the Initial View Controller.

If you check "Is Initial View Controller" in the Attributes Inspector of the View Controller, an arrow indicates that it is the View Controller at the starting point.