提醒完成处理程序崩溃-[webview VC webview:runjavascriptalertpanelwithmessage:initiated by frame:completion handler:]原因分析在WKWebView的WKUIDelegate回调方法中没有调用，(void () (void)) CompletionHandler和(void () (bool)) CompletionHandler，无论是YES还是No，都必须执行 如果当前的WebViewVC被删除，completionHandler还没有执行，就会报出这个崩溃提醒(我延迟了completionHandler的执行时间，崩溃现象再次出现) 该方法可以直接在代码上处理，无需添加额外的属性。可以通过在使用(void () (bool)) CompletionHandler和(void () (void)) CompletionHandler的WKUIDelegate的几个回调方法中添加判断来处理。 # pragma mark-wkuidelegate-(void)webview:(wk webview *)webview runjavascript alertpanelwithmessage:(ns string *)message initiated by frame:(wkframeinfo *)frame completion handler:(void(^)(void))completionhandler{ if([self . navigation controller visible viewcontroller]！= self){ completion handler()；返回；} UIAlertController * alert controller =[UIAlertController alertcontrollerwithttitle:@ " " message:message preferred style:UIAlertControllerStyleAlert]；[Alert Controller add Action:[UIAlertaction Action with title:@ " Confirm " style:UIAlertaction style cancel Handler:(UIAlertaction * Action){ completion Handler()；}]];if([self . navigation controller visible view controller]= = self){[self present view controller:alert controller animated:YES completion:nil]；} else { completion handler()；} }//显示两个按钮，通过completionHandler回调确定客户是点击确认还是取消按钮-(void)webview:(wk webview *)webview run JavaScript confirimpanelmessage:(nsstring *)message initiated by frame:(wkframeinfo *)frame completion handler:(void(^)(bool))completionhandler{ if([self . navigation controller visible viewcontroller]！= self){ completion handler(NO)；返回；} UIAlertController * alert controller =[UIAlertController alertcontrollerwithttitle:message message:nil preferred style:UIAlertControllerStyleAlert]；[Alert Controller add Action:[UIAlertaction Action with title:@ " OK " style:UIAlertaction style default Handler:(UIAlertaction * _ nonnull Action){ completion Handler(yes)；}]];[Alert Controller add Action:[UIAlertaction Action with title:@ " Cancel " Style:UIAlertaction Style Cancel Handler:(UIAlertaction * _ nonnull Action){ completion Handler(no)；}]];if([self . navigation controller visible view controller]= = self){[self present view controller:alert controller animated:YES completion:nil]；} else { completion handler(NO)；} }//显示一个带有输入框和确定按钮的，回调客户通过completion handler-(void)webview输入的内容:(wk webview *)webview runjavascripttextinputpanelwithprompt:(ns string *)提示默认文本:(ns string *)default text initiated by frame:(wkframeinfo *)frame completion handler:(void(^)(nsstring * _ nullable))completion handler { if([self . navigation controller visibleviewcontroller]！= self) { completionHandler(@“错误”)；返回；} UIAlertController * alert controller =[UIAlertController alertcontrollerwithttitle:@ " " message:nil preferred style:UIAlertControllerStyleAlert]；[alert controller addtextfieldwithconfigurationhandler:^(uitextfield * _ nonnull textfield){ }]；[Alert Controller add Action:[UIAlertaction Action with title:@ " OK " style:UIAlertaction style default Handler:(UIAlertaction * _ nonnull Action){ completion Handler(Alert Controller . text fields . lastobject . text)；}]];if([self . navigation controller visible view controller]= = self){[self present view controller:alert controller animated:YES completion:nil]；} else { completion handler(@ " error ")；}}