"This application is modifying the autolayout engine from a background thread, which can lead to en

 问题：事件在子线程中处理，多次代理回调导致可能会出现僵尸线程的报错

处理: 把代理加到异步主线程处理

dispatch_async(dispatch_get_main_queue(), ^(){
            [self.delegate xxxxx:nil];
           });