WKWebView goBack requiring two invocations - ios

Question

I'm working on a iOS app that uses WKWebView, with custom navigation buttons. We're finding that following some links will require using our Back button twice, as the first invocation seems to just reload the current page. This does not happen in mobile Safari.
What could cause goBack() to need to be called twice to actually navigate back one page, while it works correctly in Safari? Are there changes I can make in the app to correct the issue?
Note: I cannot make changes to the web site's content or structure, so any fixes would have to be in the app.
Update:
It appears the site is using JavaScript for some of its content loads. The observeValue method is not invoked at all when this happens and is probably the culprit.
import UIKit
import WebKit
import SafariServices
class LandingPageViewController: UIViewController, SFSafariViewControllerDelegate, WKUIDelegate, WKNavigationDelegate {
#IBOutlet var urlNavigationItem: UINavigationItem!
#IBOutlet var backButton: UIBarButtonItem!
#IBOutlet var forwardButton: UIBarButtonItem!
#IBOutlet var reloadButton: UIBarButtonItem!
var webView: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
webView = WKWebView()
view.addSubview(webView)
webView.addObserver(self, forKeyPath: "loading", options: .new, context: nil)
let request = URLRequest(url: url) //url is defined elsewhere
webView.navigationDelegate = self
webView.load(request)
webView.allowsBackForwardNavigationGestures = true
webView.uiDelegate = self
backButton.isEnabled = false
forwardButton.isEnabled = false
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if(keyPath == "loading"){
backButton.isEnabled = webView.canGoBack
forwardButton.isEnabled = webView.canGoForward
}
}
#IBAction func back(_ sender: UIBarButtonItem) {
webView.goBack()
}
#IBAction func forward(_ sender: UIBarButtonItem){
webView.goForward()
}
#IBAction func reload(_ sender: UIBarButtonItem) {
let request = URLRequest(url: webView.url!)
webView.load(request)
}
func webView(_ webView: WKWebView,
decidePolicyFor navigationAction: WKNavigationAction,
decisionHandler: #escaping (WKNavigationActionPolicy) -> Void) {
// Custom logic here
}
}

Answer 1

try with following delegate methods,
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: #escaping (WKNavigationActionPolicy) -> Void) {
decisionHandler(.allow)
}
func webView(_ webView: WKWebView, decidePolicyFor navigationResponse: WKNavigationResponse, decisionHandler: #escaping (WKNavigationResponsePolicy) -> Void) {
decisionHandler(.allow)
}
You have implemented one but not call decisionHandler(.allow)

Answer 2

I was facing the same issue. What worked for me was stopping the navigation and then go back.
func goBack() {
self.webView.stopLoading()
if (self.webView.canGoBack) {
self.webView.goBack()
return;
}
}