block回调刷新UI填坑

在block回调中要去刷新界面，遇到这样的问题

 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.

截图如下，英语比较挫，大概意思就是说需要在主线程中去刷新UI

错误信息

错误代码如下

_coutTimeV.timeOut = ^(){
   [weakSelf.coutTimeV endCountDown];
   [weakSelf doSomething];
};

修改后

_coutTimeV.timeOut = ^(){
   [weakSelf.coutTimeV endCountDown];
   //通知主线程去做刷新动作
   dispatch_async(dispatch_get_main_queue(), ^{
     [weakSelf doSomething];
   });
};

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小白总结，欢迎打脸指正