iOS This application is modifying...

This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

ui更新需放在主线程中执行，将原有的子线程（或block中）更新ui操作方法添加到主线程中：如下

dispatch_async(dispatch_get_main_queue(), ^{

///< 执行更新ui操作

});