iOS检查网络是否可用的代码

SCNetworkReachabilityFlags flags;
    BOOL receivedFlags;

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(CFAllocatorGetDefault(), [@"google.com" UTF8String]);
    receivedFlags = SCNetworkReachabilityGetFlags(reachability, &flags);
    CFRelease(reachability);

    //NSLog(@"idiotic flags %@", receivedFlags);

    if (!receivedFlags || (flags == 0))
    {
        return NO;
    } else {
        return YES;
    }