Error: Could not cast value of type 'UINavigationController'

Question

I want to present a view controller in FavouriteButtonHandler on a button press.

When I press the button, I get the following error:

Could not cast value o

Answer 1

It's working perfectly for me :

Pushing the PDFViewController into Navigation Stack :

   if let presentVC = self.storyboard?.instantiateViewController(withIdentifier: "PDFViewController") as? PDFViewController{
        self.navigationController?.pushViewController(presentVC, animated: true)
    }

OR

    if let presentVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "PDFViewController") as? PDFViewController {
        self.navigationController?.pushViewController(presentVC, animated: true)
    }

Please, make sure that your current viewController should belong to the top of Navigation stack before pushing anything on it.