网速监控

• 原理

（上一个时间节点的数据 - 下一时间节点的数据）/ 时间间隔 = 速率

• 获取下行流量数据

- (long long)getInterfaceBytes {
    
    struct ifaddrs* addrs;
    const struct ifaddrs* cursor;

    long long currentBytesValue = 0;
       
    if (getifaddrs(&addrs) == 0) {
        
        cursor = addrs;
        while (cursor != NULL) {
            const struct if_data* ifa_data = (struct if_data*)cursor->ifa_data;
            if (ifa_data) {
                // total number of octets received
                int receivedData = ifa_data->ifi_ibytes;
                   
                currentBytesValue += receivedData;
            }
            cursor = cursor->ifa_next;
        }
    }
    freeifaddrs(addrs);
    return currentBytesValue;
    
}

• 字节转换

- (NSString *)formatNetWork:(long long int)rate {
    if (rate <1024) {
        return [NSString stringWithFormat:@"%lldB/S", rate];
    } else if (rate >=1024&& rate <1024*1024) {
        return [NSString stringWithFormat:@"%.1fKB/S", (double)rate /1024];
    } else if (rate >=1024*1024&& rate <1024*1024*1024) {
        return [NSString stringWithFormat:@"%.2fMB/S", (double)rate / (1024*1024)];
    } else {
        return@"0Kb/S";
    };
}