New to Xcode and having an error "Thread 1: Signal SIGABRT"

Hey guys, I'm new to app development and can't seem to resolve this issue. Simulator opens the app to a white screen.

Here's what I have:

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var greetingField: UILabel!
@IBOutlet weak var nameField: UITextField!

@IBAction func submitButtonTapped(sender: AnyObject) {
    
    greetingField.text = nameField.text

}


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}