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

在開發中，有時候需要獲取流量統計信息。研究發現：通過函數getifaddrs來得到系統網絡接口的信息，網絡接口的信息，包含在if_data字段中， 有很多信息， 但我現在只關心ifi_ibytes, ifi_obytes, 應該就是接收到的字節數和發送的字節數, 加起來就是流量了。還發現，接口的名字， 有en, pdp_ip, lo等幾種形式，en應該是wifi, pdp_ip大概是3g或者gprs, lo是環回接口, 通過名字區分可以分別統計。
　　
1、導入必要頭文件

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

2、獲取3G或者GPRS的流量

//獲取3G或者GPRS的流量
/*下載流量*/

+ (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;
    
    //將bytes單位轉換
    
    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、獲取Wifi流量

//獲取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);
    
    //將bytes單位轉換
    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、通過讀取系統網絡接口信息，獲取當前iphone設備的流量相關信息，統計的是上次開機至今的流量信息.
　　　2、上面兩方法統計的結果是字符串格式