Can't cast value of type UIViewController to PatternDetailViewController

Question

Am trying to downcast a view controller to a detail view controller but can\'t. Am using Core Data (for the first time). The error is in the prepareForSegue method and reads

Answer 1

My issue is:

Not work

let aBCViewController = UIViewController(nibName: "ABCViewController", bundle: nil) as! ABCViewController
present(aBCViewController, animated: true, completion: nil)

Work

let aBCViewController = ABCViewController(nibName: "ABCViewController", bundle: nil)
present(aBCViewController, animated: true, completion: nil)