#import <sys/socket.h>
#import <netinet/in.h>
#import <arpa/inet.h>
#import <netdb.h>
#import <SystemConfiguration/SCNetworkReachability.h>
//Snip, you know we're in the implementation...
- (BOOL) connectedToNetwork
{
	// 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 = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
	SCNetworkReachabilityFlags flags;
 
	BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
	CFRelease(defaultRouteReachability);
 
	if (!didRetrieveFlags)
	{
		return NO;
	}
 
	BOOL isReachable = flags & kSCNetworkFlagsReachable;
	BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
	return (isReachable && !needsConnection) ? YES : NO;
}
 
//call like:
-(void) start {
	if (![self connectedToNetwork]) {
                UIAlertView *alert = [[UIAlertView alloc] 
                         initWithTitle:@"Network Connection Error" 
                         message:@"You need to be connected to the internet to use this feature." 
                         delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
		[alert show];
		[alert release];
        } else {
             //do something 
        }
}