Getting error when I am going from 1st view to 2nd view controller

import UIKit

import CoreData

@main. ---- here I am getting error in App delegate file

class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        // Override point for customization after application launch.

        return true

The error is reported in AppDelegate (that where finally the app crashes), but that is not the place of initial error.

.

this class is not key value coding-compliant for the key onSubmitClick

That may be due to an non connected or ill connected IBOutlet / IBAction.

Please explain in detail how you transition from 1st VC to 2nd VC.

Is it a segue in an UIButton ?

And show code.