使用Reachability类判断iOS设备的当前网络连接类型

- (NetworkStatus) networkStatusForFlags: (SCNetworkReachabilityFlags) flags
{
    if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
    {
        return NotReachable;
    }
    
    BOOL retVal = NotReachable;
    
    if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
    {
        // if target host is reachable and no connection is required
        //  then we'll assume (for now) that your on Wi-Fi
        retVal = ReachableViaWiFi;
    }
    
    
    if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
         (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
    {
        // ... and the connection is on-demand (or on-traffic) if the
        //     calling application is using the CFSocketStream or higher APIs
        if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
        {
            // ... and no [user] intervention is needed
            retVal = ReachableViaWiFi;
        }
    }
    
    if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
    {
        if((flags & kSCNetworkReachabilityFlagsReachable) == kSCNetworkReachabilityFlagsReachable) {
            if ((flags & kSCNetworkReachabilityFlagsTransientConnection) == kSCNetworkReachabilityFlagsTransientConnection) {
                retVal = ReachableVia3G;
                if((flags & kSCNetworkReachabilityFlagsConnectionRequired) == kSCNetworkReachabilityFlagsConnectionRequired) {
                    retVal = ReachableVia2G;
                }
            }
        }
    }
    return retVal;
}
 
//检查当前网络连接是否正常
-(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) {
        printf("Error. Count not recover network reachability flags/n");
        return NO;
    }
    
    BOOL isReachable = flags & kSCNetworkFlagsReachable;
    BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
    return (isReachable && !needsConnection) ? YES : NO;
}
 
//检查网络连接类型
-(void)checkNetworktype:(id)sender{
    NSString *connectionKind;
    if ([self connectedToNetWork]) {
        hostReach = [Reachability reachabilityWithHostName:@"www.google.com"];
        switch ([hostReach currentReachabilityStatus]) {
            case NotReachable:
                connectionKind = @"没有网络链接";
                break;
            case ReachableViaWiFi:
                connectionKind = @"当前使用的网络类型是WIFI";
                break;
            case ReachableVia3G:
                connectionKind = @"当前使用的网络链接类型是WWAN（3G）";
                break;
            case ReachableVia2G:
                connectionKind = @"当前使用的网络链接类型是WWAN（2G）";
                break;   
            default:
                break;
        }
    }else {
        connectionKind = @"没有网络链接";
    }
}