怎么判断iphone是否联网

+(BOOL)isNetworkReachable{ // Create zero addy struct sockaddr_in zeroAddress; bzero(&zeroAddress, sizeof(zeroAddress));zeroAddress.sin_len = sizeof(zeroAddress);zeroAddress.sin_family = AF_INET;// Recover reachability flags SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddres(NULL, (struct sockaddr *)&zeroAddress);SCNetworkReachabilityFlags flags; BOOL didRetrieveFlags = SCNetworkReachabilityGetFlag(defaultRouteReachability, &flags); CFRelease(defaultRouteReachability); if (!didRetrieveFlags) {                  return NO;               }}

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