iOS 混合网页开发 问题

_weak typeof(self)weakSelf = self;
    
    JSContext *tContext = [weakSelf.webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];
    
    tContext[@"jsredirect"] = ^(){
        
        NSArray *tArgs = [JSContext currentArguments];
        JSValue *tJSValue = [tArgs firstObject];
        
        @try
        {
            NSDictionary *tActionValueDic = [tJSValue toDictionary];
            
            NSLog(@"JSValue:%@", tActionValueDic);
            
            NSString *tUrlStr = tActionValueDic[@"url"];
            
            if ([tUrlStr isEqualToString:@"chartDispose"]) {
                [[NSUserDefaults standardUserDefaults] setInteger:0 forKey:@"WebKitCacheModelPreferenceKey"];
                [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"WebKitDiskImageCacheEnabled"];
                [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"WebKitOfflineWebApplicationCacheEnabled"];
                [[NSUserDefaults standardUserDefaults] synchronize];
            }else{
                CGGradeJumpWebViewController *vc = [[CGGradeJumpWebViewController alloc]init];
                vc.urlStr = tUrlStr;
                NSLog(@"Current Thread:%@",[NSThread currentThread]);
                dispatch_async(dispatch_get_main_queue(), ^{
                    //UI修改
                    NSLog(@"Current Thread:%@",[NSThread currentThread]);
                    [weakSelf.navigationController pushViewController:vc animated:YES];
                });
            }
            
            
        }
        @catch (NSException *exception)
        {
            NSLog(@"exception:%@", exception);
        }
    };