In Swift if you want to check the Wifi connection in your device then use following code.

This is a function which returns Reachability instance (reachability class object) value as a returnvalue for wifi connection availability.

+ (instancetype)reachabilityForLocalWiFi
{
    struct sockaddr_in localWifiAddress;
    bzero(&localWifiAddress, sizeof(localWifiAddress));
    localWifiAddress.sin_len = sizeof(localWifiAddress);
    localWifiAddress.sin_family = AF_INET;

    // IN_LINKLOCALNETNUM is defined in  as 169.254.0.0.
    localWifiAddress.sin_addr.s_addr = htonl(IN_LINKLOCALNETNUM);

    Reachability* returnValue = [self reachabilityWithAddress: &localWifiAddress];
    if (returnValue != NULL)
    {
        returnValue->_alwaysReturnLocalWiFiStatus = YES;
    }

    return returnValue;
}

Hope this will help you. Happy Coding!!!