iphone判斷網絡鏈接是否正常的代碼

+(BOOL)connectedToNetwork{
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress;, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;


SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress;);
SCNetworkReachabilityFlags flags;

BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags;);
CFRelease(defaultRouteReachability);

if (!didRetrieveFlags)
{
    NSLog(@"Error. Could not recover network reachability flags");
    return NO;
}

BOOL isReachable = flags & kSCNetworkFlagsReachable;
BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
return (isReachable && !needsConnection) ? YES : NO;

}</pre>