The WKWebView was invalidated" UserInfo={NSLocalizedDescription=The WKWebView was invalidated - swift

Question

I am trying to retrieve html using webView. I don't want to write my webView code in the view file therefore trying to implement it in a different class. Below is my code.
class BlobHelper: NSObject,WKNavigationDelegate{
let webView = WKWebView()
func getLyrics(){
let url = URL(string: "https://Blob")!
let request = URLRequest(url: url)
webView.load(request)
webView.evaluateJavaScript("document.getElementsByTagName('html')[0].innerHTML;", completionHandler: {(value,error)in
print(value)
print(error)
})
}
func webView(_ webView: WKWebView,didFinish navigation: WKNavigation!) { print("loaded") }
When I execute the code I get Optional(Error Domain=WKErrorDomain Code=3 "The WKWebView was invalidated" UserInfo={NSLocalizedDescription=The WKWebView was invalidated}).
What I tried
I was able to retrieve html using static but couldn't get the didFinish to call after loading.
Any help is appreciated.

Answer 1

class ViewController: UIViewController, WKNavigationDelegate {
var webView = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
let configuration = WKWebViewConfiguration()
self.webView = WKWebView(frame: .zero, configuration: configuration)
webView.navigationDelegate = self
let url = URL(string: "https://stackoverflow.com")!
let request = URLRequest(url: url)
webView.load(request)
self.view = webView
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
webView.evaluateJavaScript("document.getElementsByTagName('html')[0].innerHTML;", completionHandler: { (value,error)in
print(value)
})
}}