IOS 常遇到的报错警告 以及 解决办法

1.  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. 错误

用下面的代码把出错的代码包括起来就好了,意思是回到主线程

dispatch_async(dispatch_get_main_queue(), ^(void){

 

});