Check Internet Connection

static BOOL checkNetwork = YES;
    if (checkNetwork) { // Since checking the reachability of a host can be expensive, cache the result and perform the reachability check once.
        checkNetwork = NO;
 
        Boolean success;    
        const char *host_name = "earthquake.usgs.gov";
 
        SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, host_name);
        SCNetworkReachabilityFlags flags;
        success = SCNetworkReachabilityGetFlags(reachability, &flags);
        _isDataSourceAvailable = success && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired);
        CFRelease(reachability);
    }
    return _isDataSourceAvailable;