UIAlertView

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.

UIAlertView已经被苹果官方禁用一段时间，新的工程建议使用UIAlertController替代。

今天做个小demo用了一下，发现代码有屎黄的警告不说，运行起来还会在debug区打印出上面一段提示。意思大致是说它使用了子进程导致该异常。