转自：http://www.cnblogs.com/jukaiit/p/5730228.html

在开发中，有时候需要获取流量统计信息。研究发现：通过函数getifaddrs来得到系统网络接口的信息，网络接口的信息，包含在if_data字段中， 有很多信息， 但我现在只关心ifi_ibytes, ifi_obytes, 应该就是接收到的字节数和发送的字节数, 加起来就是流量了。还发现，接口的名字， 有en, pdp_ip, lo等几种形式，en应该是wifi, pdp_ip大概是3g或者gprs, lo是环回接口, 通过名字区分可以分别统计。
　　
1、导入必要头文件

#include <ifaddrs.h>
#include <sys/socket.h>
#include <net/if.h>

2、获取3G或者GPRS的流量

//获取3G或者GPRS的流量
/*下载流量*/

+ (NSString *)getGprs3GFlowIOBytes
{
    
    struct ifaddrs *ifa_list = 0, *ifa;
    if (getifaddrs(&ifa_list) == -1)
    {
        return 0;
    }
    
    uint32_t iBytes = 0;
    uint32_t oBytes = 0;
    
    for (ifa = ifa_list; ifa; ifa = ifa->ifa_next)
    {
        if (AF_LINK != ifa->ifa_addr->sa_family)
            continue;
        
        if (!(ifa->ifa_flags & IFF_UP) && !(ifa->ifa_flags & IFF_RUNNING))
            continue;
        
        if (ifa->ifa_data == 0)
            continue;
        
        //3G或者GPRS
        if (!strcmp(ifa->ifa_name, "pdp_ip0"))
        {
            struct if_data *if_data = (struct if_data *)ifa->ifa_data;
            
            iBytes += if_data->ifi_ibytes;
            oBytes += if_data->ifi_obytes;
            NSLog(@"%s :iBytes is %d, oBytes is %d",
                  ifa->ifa_name, iBytes, oBytes);
        }
    }
    
    freeifaddrs(ifa_list);
    
    uint32_t bytes = 0;
    
    bytes = iBytes + oBytes;
    
    //将bytes单位转换
    
    if(bytes < 1024)        // B
    {
        return [NSString stringWithFormat:@"%dB", bytes];
    }
    else if(bytes >= 1024 && bytes < 1024 * 1024)    // KB
    {
        return [NSString stringWithFormat:@"%.1fKB", (double)bytes / 1024];
    }
    else if(bytes >= 1024 * 1024 && bytes < 1024 * 1024 * 1024)    // MB
    {
        return [NSString stringWithFormat:@"%.2fMB", (double)bytes / (1024 * 1024)];
    }
    else    // GB
    {
        return [NSString stringWithFormat:@"%.3fGB", (double)bytes / (1024 * 1024 * 1024)];
    }
}

3、获取Wifi流量

//获取Wifi流量
+ (NSString *)getGprsWifiFlowIOBytes {
    struct ifaddrs *ifa_list = 0, *ifa;
    if (getifaddrs(&ifa_list) == -1) {
        return 0;
    }
    uint32_t iBytes = 0;
    uint32_t oBytes = 0;
    for (ifa = ifa_list; ifa; ifa = ifa->ifa_next) {
        if (AF_LINK != ifa->ifa_addr->sa_family)
            continue;
        if (!(ifa->ifa_flags & IFF_UP) && !(ifa->ifa_flags & IFF_RUNNING))
            continue;
        if (ifa->ifa_data == 0)
            continue;
        
        //Wifi
        if (strncmp(ifa->ifa_name, "lo", 2)) {
            struct if_data *if_data = (struct if_data *)ifa->ifa_data;
            iBytes += if_data->ifi_ibytes;
            oBytes += if_data->ifi_obytes;
            NSLog(@"%s :iBytes is %d, oBytes is %d", ifa->ifa_name, iBytes, oBytes);
        }
    }
    
    freeifaddrs(ifa_list);
    
    uint32_t bytes = 0;
    
    bytes = iBytes+oBytes;
    
    NSLog(@"%d",bytes);
    
    //将bytes单位转换
    if(bytes < 1024)        // B
    {
        return [NSString stringWithFormat:@"%dB", bytes];
    }
    else if(bytes >= 1024 && bytes < 1024 * 1024)    // KB
    {
        return [NSString stringWithFormat:@"%.1fKB", (double)bytes / 1024];
    }
    else if(bytes >= 1024 * 1024 && bytes < 1024 * 1024 * 1024)    // MB
    {
        return [NSString stringWithFormat:@"%.2fMB", (double)bytes / (1024 * 1024)];
    }
    else    // GB
    {
        return [NSString stringWithFormat:@"%.3fGB", (double)bytes / (1024 * 1024 * 1024)];
    }
}

注意：1、通过读取系统网络接口信息，获取当前iphone设备的流量相关信息，统计的是上次开机至今的流量信息.
　　　2、上面两方法统计的结果是字符串格式