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

It looks like you are using a navigation controller judging by your viewDidLoad() in PatternDetailViewController.

If PatternDetailViewController is embedded in a UINavigatonController then the navigation controller will be segue.destinationViewController.

Get the PatternDetailViewController like this:

let vc: UINavigationController = segue.destinationViewController as! UINavigationController
let detailVC = vc.topViewController as! PatternDetailViewController
detailVC.pattern = self.selectedPattern