If you mean to get the content height of the html in WKWebView to make it non-scrollable inside UIScrollView, then read on.

You need to observe (via delegate) the content height of your webView. I'm giving you these steps, since you quite know what you're doing, and you're almost there.

Make an outlet out of your webView height constraint

@IBOutlet weak var constraint_WebViewHeight: NSLayoutConstraint!

Subscribe to webView's delegate

This will let you know (your controller when your webView has finished loading the contents of your site.

self.webView.navigationDelegate = self

Conform to protocol

Inside the didFinish navigation method of WKNavigationDelegate, you then adjust the constant of your webView height constraint. Put some animation if you want to :)

extension ViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            self.constraint_WebViewHeight.constant = webView.scrollView.contentSize.height
        }
    }
}

Finally, fix your constraints.

a. Remove your imageView bottom constraint. b. Add bottom constraint to your save button to the scrollView.

This will make your scrollView scrollable.

Voila! This yields this result.

I hope this helps!

As per the understanding you want webview not to scroll well if the page is bigger than your screen it will scroll right? To show the full page. Although you can change the isscrollingenabled to false from interface builder or from code by using object of scrollview. To set full height give constraint 0,0,0,0 from all sides and it will surely stretch to whole screen

It's wrong approach. You should use WKWebView's scrollView.

You need reserve space for image and button with html margins using javascript

[NSString stringWithFormat:@"document.body.style.margin = '%dpx %dpx %dpx %dpx'", (int)margins.top, (int)margins.right, (int)margins.bottom, (int)margins.left]

or directly in html body if you able to access it.

Add imageview and button into WKWebView's scrollView.