xcode报错：Declaration of ‘struct sockaddr_in’ will not be visible outside of this function

+ (Reachability*) reachabilityWithAddress: (const struct sockaddr_in*) hostAddress;

Declaration of 'struct sockaddr_in' will not be visible outside of this function

解决办法很简单，Reachability.h中最前面添加头文件:#import <netinet/in.h>