Can't resize wkwebview in ViewController

This is first app I'm building. In view controller I'm creating webview and it works fine. My problem is that I want to show native button at the top if user navigate to url that is not ours. For e.g. twitter social login. I need to create offset from the top but whatever I try I can't seem to change the height of the view in which WKwebview loads. Story board only contains safearea.

Any help appreciated

var webView: WKWebView!
override func loadView() {
webView = WKWebView()
webView.navigationDelegate = self
webView.uiDelegate = self
view = webView

override func viewDidLoad() {