Migrating from UIWebView to WKWebView

UIWebView => WKWebView Equivalent

UIWebViewDelegate => WKNavigationDelegatedelegate => navigationDelegatedidFailLoadWithError => didFailNavigationwebViewDidFinishLoad => didFinishNavigationwebViewDidStartLoad => didStartProvisionalNavigationshouldStartLoadWithRequest => decidePolicyForNavigationAction

About shouldStartLoadWithRequest you can write:

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {    print("webView:\(webView) decidePolicyForNavigationAction:\(navigationAction) decisionHandler:\(decisionHandler)")        switch navigationAction.navigationType {        case .linkActivated:        if navigationAction.targetFrame == nil {            self.webView?.loadRequest(navigationAction.request)        }        if let url = navigationAction.request.url, !url.absoluteString.hasPrefix("http://www.myWebSite.com/example") {            UIApplication.shared.open(url)            print(url.absoluteString)            decisionHandler(.cancel)        return        }        default:            break    }        if let url = navigationAction.request.url {        print(url.absoluteString)    }    decisionHandler(.allow)}

And for the didFailLoadWithError:

func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {    print("webView:\(webView) didFailNavigation:\(navigation) withError:\(error)")    let testHTML = Bundle.main.path(forResource: "back-error-bottom", ofType: "jpg")    let baseUrl = URL(fileURLWithPath: testHTML!)    let htmlString = "myErrorInHTML"    self.webView.loadHTMLString(htmlString, baseURL: baseUrl)}

Here is the Objective-C methods for the migration:

1. shouldStartLoadWithRequest -> decidePolicyForNavigationAction

Remember to call the decisionHandler:

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {       if (navigationAction.navigationType == WKNavigationTypeLinkActivated) {       }       NSString *url = [navigationAction.request.URL query];                       decisionHandler(WKNavigationActionPolicyAllow);}

2. webViewDidStartLoad -> didStartProvisionalNavigation

- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {}

3. webViewDidFinishLoad -> didFinishNavigation

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {}

4. didFailLoadWithError -> didFailNavigation

- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {}

Migrating UIWebView to WKWebView, Swift 4:

Equivalent of shouldStartLoadWithRequest:

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {    var action: WKNavigationActionPolicy?    defer {        decisionHandler(action ?? .allow)    }    guard let url = navigationAction.request.url else { return }    print(url)    if navigationAction.navigationType == .linkActivated, url.absoluteString.hasPrefix("http://www.example.com/open-in-safari") {        action = .cancel                  // Stop in WebView        UIApplication.shared.openURL(url) // Open in Safari    }}

Equivalent of webViewDidStartLoad:

func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {    print(String(describing: webView.url))}

Equivalent of didFailLoadWithError:

func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {    let nserror = error as NSError    if nserror.code != NSURLErrorCancelled {        webView.loadHTMLString("404 - Page Not Found", baseURL: URL(string: "http://www.example.com/"))    }}

Equivalent of webViewDidFinishLoad:

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {    print(String(describing: webView.url))}