Error: Unexpectedly found nil while implicitly unwrapping an Optional value

I have a error that after i build my code and i'm not sure how to fix this.
class AddNotesController : UIViewController {

var delegate: AddNotesDelegate?

@IBOutlet weak var addNote: UIBarButtonItem!

@IBOutlet weak var textfield: UITextView!



override func viewDidLoad() {
    super.viewDidLoad()
    
    view.addSubview(textfield)
    textfield!.becomeFirstResponder()

   
}

The errors that i received would be view.addSubview(textfield)

@chapffy did you hook all outlets and do they have correct naming? and if you're using IBOutlets why bother adding these views manually?

see:
https://www.hackingwithswift.com/example-code/xcode/what-is-an-iboutlet
https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/ConnectTheUIToCode.html