How to check for local Wi-Fi (not just cellular connection) using iPhone SDK?
- by Michael
I'm currently using the following to check whether Wi-Fi is available for my application:
#import <SystemConfiguration/SystemConfiguration.h>
static inline BOOL addressReachable(const struct sockaddr_in *hostAddress);
BOOL localWiFiAvailable()
{
struct sockaddr_in localWifiAddress;
bzero(&localWifiAddress, sizeof(localWifiAddress));
localWifiAddress.sin_len = sizeof(localWifiAddress);
localWifiAddress.sin_family = AF_INET;
// IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0
localWifiAddress.sin_addr.s_addr = htonl(IN_LINKLOCALNETNUM);
return addressReachable(&localWifiAddress);
}
static inline BOOL addressReachable(const struct sockaddr_in *hostAddress)
{
const SCNetworkReachabilityRef target =
SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault,
(const struct sockaddr *)hostAddress);
if (target != NULL)
{
SCNetworkReachabilityFlags flags = 0;
const BOOL reachable = SCNetworkReachabilityGetFlags(target, &flags);
CFRelease(target);
return reachable && (flags & kSCNetworkFlagsReachable);
}
return NO;
}
This, however, does not return NO as it should when the iPhone is connected only to a cellular network but not a Wi-Fi network. Does anyone know how to fix this?
Edit
So this is what I ended up using:
#import <arpa/inet.h> // For AF_INET, etc.
#import <ifaddrs.h> // For getifaddrs()
#import <net/if.h> // For IFF_LOOPBACK
BOOL localWiFiAvailable()
{
struct ifaddrs *addresses;
struct ifaddrs *cursor;
BOOL wiFiAvailable = NO;
if (getifaddrs(&addresses) != 0) return NO;
cursor = addresses;
while (cursor != NULL) {
if (cursor -> ifa_addr -> sa_family == AF_INET
&& !(cursor -> ifa_flags & IFF_LOOPBACK)) // Ignore the loopback address
{
// Check for WiFi adapter
if (strcmp(cursor -> ifa_name, "en0") == 0) {
wiFiAvailable = YES;
break;
}
}
cursor = cursor -> ifa_next;
}
freeifaddrs(addresses);
return wiFiAvailable;
}
Thanks "unforgiven" (and Matt Brown apparently).
