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.

在子執行緒中操作UI相關的操作了；

修改方式，將操作UI的程式碼塊（注意程式碼塊裡不能有return）放到如下巨集定義裡

#ifndef dispatch_main_async_safe    
#define dispatch_main_async_safe(block)\
    if (dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL) == dispatch_queue_get_label(dispatch_get_main_queue())) {\
        block();\
    } else {\
        dispatch_async(dispatch_get_main_queue(), block);\
    }
#endif

//主執行緒同步佇列  https://blog.csdn.net/qq_26341621/article/details/50156157
#define dispatch_main_sync_safe(block)\
    if ([NSThread isMainThread]) {\
        block();\
    } else {\
        dispatch_sync(dispatch_get_main_queue(), block);\
    }
//主執行緒非同步佇列
#define dispatch_main_async_safe(block)\
    if ([NSThread isMainThread]) {\
        block();\
    } 
 
else {\
        dispatch_async(dispatch_get_main_queue(), block);\
    }
//用法
  dispatch_main_async_safe(^{
                    //需要執行的程式碼片段;
                });

如果你放到程式碼塊中的程式碼有return操作，就會報錯：

No matching function for call to 'dispatch_async' in my drawing code：You start drawing on one thread, then finish it on another thread. That's a ticking time bomb.