Web View crashes - ios

Question

Hello and thanks for reading this,
I'm building a simple app with 2-3 tabs (view controllers), and the first one is some kind of converter (miles to km), it's fine, and the second viewcontroller has to have a "webview" element.
So, when I build a separate app with only ONE view controller, (with "import WebKit") it works fine:
super.viewDidLoad()
webview.load(URLRequest(url: URL(string: "https://www.google.com")!))
BUT when I copy this to my 2-tabbed app code under the line #super.viewDidLoad()#, it crashes saying "Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value".
I'm really new with this all, so I don't know how to fix this. And I didn't find solutions to similar problem on this forum. Thank you in advance!
p.s. how am I creating web view - visually add it. I see the tip to create it by coding, I will try, thank you
p.p.s. Im adding here my code:
import UIKit
import SafariServices
import WebKit
extension String {
func toDouble() -> Double? {
return NumberFormatter().number(from: self)?.doubleValue
} }
class ViewController: UIViewController {
#IBOutlet var mileField: UITextField!
#IBOutlet var mileResult: UILabel!
#IBOutlet var meters: UILabel!
#IBOutlet var cmeters: UILabel!
#IBAction func mileButton(_ sender: UIButton) {
let mile: Double = mileField.text?.toDouble() ?? 0
let km = mile * 1.6
let m = km * 1000
let cm = m * 100
meters.text = String(m)+" m"
mileResult.text = String(km)+" km"
cmeters.text = String(cm)+" cm"
}
#IBOutlet var vw: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
vw.load(URLRequest(url: URL(string: "google.com")!)) // this is where I got Fatal error blah blah blah
}
#IBAction func bTapped() {
let vc = SFSafariViewController(url: URL(string: "https://www.apple.com")!)
present(vc, animated: true) // this works fine but I need to use webview element
}
}
a little screenshot

Answer 1

Declare your two view controllers. Also please assign this class names to your view controller in storyboard.
https://i.stack.imgur.com/BDoY6.png
class ViewController1: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
class ViewController2: UIViewController {
#IBOutlet var webview: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
webview.load(URLRequest(url: URL(string: "https://www.google.com")!))
}
}