首先需要開啟一個(gè)定時(shí)器，每隔1S獲取一次當(dāng)前網(wǎng)速

#pragma mark - 計(jì)時(shí)器
- (NSTimer *)timer{
    if(!_timer){
        _timer =[NSTimer timerWithTimeInterval:1 target:self selector:@selector(currentNetSpeed) userInfo:nil repeats:YES];
        [_timer setFireDate:[NSDate distantFuture]];
        [[NSRunLoop currentRunLoop] addTimer:_timer forMode:NSDefaultRunLoopMode];
    }
    return _timer;
}
#pragma mark 暫停
- (void)distantFutureTimer{
    [self.timer setFireDate:[NSDate distantFuture]];
}
#pragma mark 開始
- (void)startTimer{
    [self.timer setFireDate:[NSDate distantPast]];
}
#pragma mark 停止
- (void)stopTimer{
    [self.timer  invalidate];
    self.timer = nil;
}

然后開始獲取網(wǎng)速：

引入頭文件:

#include <arpa/inet.h>
#include <ifaddrs.h>
#include <net/if.h>
#include <net/if_dl.h>

相關(guān)代碼：

#pragma mark 當(dāng)前網(wǎng)速
- (void)currentNetSpeed {
    struct ifaddrs *ifa_list = 0, *ifa;
    if (getifaddrs(&ifa_list) == -1) return;
    
    uint32_t iBytes = 0;
    uint32_t oBytes = 0;
    uint32_t allFlow = 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;
        
        // network
        if (strncmp(ifa->ifa_name, "lo0", 2)) {
            struct if_data* if_data = (struct if_data*)ifa->ifa_data;
            iBytes += if_data->ifi_ibytes;
            oBytes += if_data->ifi_obytes;
            allFlow = iBytes + oBytes;
        }
    }
    
    freeifaddrs(ifa_list);
    if (_iBytes != 0) {
        _downloadNetSpeed = [[self stringWithbytes:iBytes - _iBytes] stringByAppendingString:@"/s"];
    }
    _iBytes = iBytes;
    
    if (_oBytes != 0) {
        _uploadNetSpeed = [[self stringWithbytes:oBytes - _oBytes] stringByAppendingString:@"/s"];
    }
    _oBytes = oBytes;
}

#pragma mark 轉(zhuǎn)換
- (NSString *)stringWithbytes:(int)bytes {
    if (bytes < 1024) { // B
        return [NSString stringWithFormat:@"%dB", bytes];
    } else if (bytes >= 1024 && bytes < 1024 * 1024) { // KB
        return [NSString stringWithFormat:@"%.0fKB", (double)bytes / 1024];
    } else if (bytes >= 1024 * 1024 && bytes < 1024 * 1024 * 1024) { // MB
        return [NSString stringWithFormat:@"%.1fMB", (double)bytes / (1024 * 1024)];
    } else { // GB
        return [NSString stringWithFormat:@"%.1fGB", (double)bytes / (1024 * 1024 * 1024)];
    }
}

這里我選擇使用lo0判斷，類似的參數(shù)還有很多，比如lo、en0、pdp_ip0，具體代表什么意思可以參考mac ifconfig解釋

可以知道lo0是loopback的意思，具體意思查看loopback，用途可以參考loopback（本地回環(huán)）接口的作用，在里面第12條：

12、NetFlow Flow-Export
從一個(gè)路由器向NetFlow采集器傳送流量數(shù)據(jù)，以實(shí)現(xiàn)流量分析和計(jì)費(fèi)目的，將路由器的Router的Loopback地址作為路由器所有輸出流量統(tǒng)計(jì)數(shù)據(jù)包的源地址，可以在服務(wù)器或者是服務(wù)器外圍提供更精確，成本更低的過(guò)濾配置。