iphone判断当前网络连接类型

​Reachability只能区分出无网络、wifi和wwan(2G&2.5G&3G)类型的网络连接类型，只需重构networkStatusForFlags方法，即可详细区分出2G与3G网络 ​
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1. [代码][C/C++]代码     
//Reachability.m 中 networkStatusForFlags 方法重构
- (NetworkStatus) networkStatusForFlags: (SCNetworkReachabilityFlags) flags
{
if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
{
return NotReachable;
}
    
BOOL retVal = NotReachable;

if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
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// 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)
        {jquery特效
            // ... 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 ");
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";
}
}