Completion handler passed to -[WKPrivateNavigationDelegate webView:decidePolicyForNavigationAction:decisionHandler:] was called more than once

[lianweiqin]

- (void)webView:(WKWebView *)webView
decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    if (webView != _webView) { return; }
    NSURL *url = navigationAction.request.URL;
    __strong typeof(_webViewDelegate) strongDelegate = _webViewDelegate;

    if ([_base isCorrectProcotocolScheme:url]) {
        if ([_base isBridgeLoadedURL:url]) {
            [_base injectJavascriptFile];
        } else if ([_base isQueueMessageURL:url]) {
            [self WKFlushMessageQueue];
        } else {
            [_base logUnkownMessage:url];
        }
        **decisionHandler(WKNavigationActionPolicyCancel);     //  executed**
    }
    
    if (strongDelegate && [strongDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)]) {
        **[_webViewDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];          //  executed** 
    } else {
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}

I implement the selector @selector(webView:decidePolicyForNavigationAction:decisionHandler:)
and execute "decisionHandler(WKNavigationActionPolicyAllow);"

It seems the decisionHandler can be called twice and cause the crash.
No such thing has happened before...

[lokimeyburg]

(I updated your issue to make your code render in Markdown... makes it easier to read)

Your conditionals allow for more than one handler to be called. Perhaps try and make the statements mutually exclusive?

    if ([_base isCorrectProcotocolScheme:url]) {
       // ...
        decisionHandler(WKNavigationActionPolicyCancel);
    } else if (strongDelegate && ... ) {
        [_webViewDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
    } else {
        decisionHandler(WKNavigationActionPolicyAllow);
    }

[yudun1989]

same issue. I met this problem on iOS 11 devices.

[rollingstoneW]

It should be this?

[wunshine]

got the same problem and not fix yet

[ifwrite]

add return; . under decisionHandler(WKNavigationActionPolicyCancel);

[iPermanent]

• (void)webView:(WKWebView *)webView
  decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
  decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
  if (webView != _webView) { return; }
  NSURL *url = navigationAction.request.URL;
  __strong typeof(_webViewDelegate) strongDelegate = _webViewDelegate;

  if ([_base isCorrectProcotocolScheme:url]) {
  if ([_base isBridgeLoadedURL:url]) {
  [_base injectJavascriptFile];
  } else if ([_base isQueueMessageURL:url]) {
  [self WKFlushMessageQueue];
  } else {
  [_base logUnkownMessage:url];
  }
  I disabled this code first
  //decisionHandler(WKNavigationActionPolicyCancel);
  }

  if (strongDelegate && [strongDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)]) {
  //Here you need to add some code judge if it's the nav by jsbridge then cancel it,
  if ([[URL.absoluteString lowercaseString] hasPrefix:@"https://wvjb_queue_message/"] || [[URL.absoluteString lowercaseString] hasPrefix:@"wvjbscheme://"]) {
  decisionHandler(WKNavigationActionPolicyCancel);
  }else{
  decisionHandler(WKNavigationActionPolicyAllow);
  }
  the code upon is my way to deal it. Hope can help you fix this problem
  [_webViewDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler]; // executed**
  } else {
  decisionHandler(WKNavigationActionPolicyAllow);
  }
  }

[iPermanent]

the code need to be added in your own delegate, and delete the cancel action decisionHandler(WKNavigationActionPolicyCancel); in WKWebViewJavascriptBridge.m

[pilot34]

Hm, why this issue is closed? I think, it is not fixed in the last version.

[iPermanent]

I think it's duplicate with the others, the same issues has exist already. It's not fixed at all.

[iosfighterlb]

Adding 'return'. Can't solve the problem on me.

It seems some sutiation it doesn't enter ： “ if ([_base isWebViewJavascriptBridgeURL:url]) ”
For example , if you only use WKWebView.

i fix this bug with adding these code in Delegate method:

    WebViewJavascriptBridgeBase *base = [[WebViewJavascriptBridgeBase alloc] init];
    if ([base isWebViewJavascriptBridgeURL:navigationAction.request.URL])
    {
        return;
    }  // Add this IF statement in my project,  don`t need modify WebViewJavascriptBridge`s source code.
       // fixd 'Completion handler passed to -[WKWebViewJavascriptBridge webView:decidePolicyForNavigationAction:...
    decisionHandler(WKNavigationActionPolicyAllow);

With these, you can compulsively enter IF and execute return .

[marcuswestin]

Fixed in latest release (6.0.3)

[Dandre126]

• (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler
  {
  if (webView != _webView) {
  return;
  }
  NSURL *url = navigationAction.request.URL;
  if ([navigationAction.request.URL.scheme.lowercaseString isEqualToString:@"pingchang"]) {
  if (![self.jsHelper shouldLoadURLRequestWithURL:navigationAction.request.URL]) {
  decisionHandler(WKNavigationActionPolicyCancel);
  return; // iOS11或xcode9中，此处必须要加一个return，否则就会报上述错误。加了return就可以解决。
  }
  }else if ([url.scheme.lowercaseString isEqualToString:@"http"] ||
  [url.scheme.lowercaseString isEqualToString:@"https"]) {
  _seTipLabel.text = [NSString stringWithFormat:@"此内容由 %@ 提供",url.host];
  }

  decisionHandler(WKNavigationActionPolicyAllow);
  }

[housenkui]

Xcode 8.2 gave me an error if i use Iphone, but if i use Simulator that is ok.

what should i do?

If i user Xcode 9.2 that do well both in Iphone and Simulator.

[iPermanent]

You should declare an interface by protocol at the .h file, so the xcode can recognize this. And by the way, we always use the latest version Xcode to avoid strange problems on iOS, I recommend you to do it as well.

[Prathapreddy26]

What is the purpose of this method?

• (void)webView:(WKWebView *)webView didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential * _Nullable))completionHandler;
  ?