iOS 混合网页开发 xcode7 线程问题

xcode6是没有问题的

在利用JavaScriptCore与H5交互时出现异常提示：

This application is modifying the autolayout engine from a background thread, which can lead to engine corruption and weird crashes.  This will cause an exception in a future release.

解决办法是：交互的跳转要在主线程进行

 dispatch_async(dispatch_get_main_queue(), ^{
                    //UI修改
                    NSLog(@"Current Thread:%@",[NSThread currentThread]);
                    [weakSelf.navigationController pushViewController:vc animated:YES];
                });