ios - 在 macOS 中创建 C 定时器

Question

我想知道如何在 macOS/iOS 中创建计时器。在linux中你可以使用time.h类的timer_create()函数来创建它，但在macOS/iOS中这个函数不存在。

类似于 NSTimer (objective-c)，但使用 C 语言。

谢谢

Answer 1

更新 Grand Central Dispatch 的链接后计时器(Apple's page)在之前的答案中，我为两个计时器创建了一些示例代码。应该注意的是，这适用于 FreeBSD 和 MacOS，但不适用于 Linux(没有 GCD 支持)。该示例创建了两个事件计时器，一个触发 0.2 秒，另一个触发 0.5 秒，总共触发 20 次。执行开始之前有 1 秒的延迟。不使用 sleep() 函数。

#include <dispatch/dispatch.h>
#include <stdio.h>
#include <stdlib.h>

int i = 0;
dispatch_queue_t queue;
dispatch_source_t timer1;
dispatch_source_t timer2;


void sigtrap(int sig)
{
    dispatch_source_cancel(timer1);
    dispatch_source_cancel(timer2);
    printf("CTRL-C received, exiting program\n");
    exit(EXIT_SUCCESS);
}

void vector1(dispatch_source_t timer)
{
        printf("a: %d\n", i);
        i++;
        if (i >= 20) 
        {
            dispatch_source_cancel(timer);
        }   
}
void vector2(dispatch_source_t timer)
{
        printf("b: %d\n", i);
        i++;
        if (i >= 20)  //at 20 count cancel the 
        {
            dispatch_source_cancel(timer);
        }   
}

int main(int argc, const char* argv[]) {

    signal(SIGINT, &sigtrap);   //catch the cntl-c
    queue = dispatch_queue_create("timerQueue", 0);

    // Create dispatch timer source
    timer1 = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    timer2 = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    
    // Set block for dispatch source when catched events
    dispatch_source_set_event_handler(timer1, ^{vector1(timer1);});
    dispatch_source_set_event_handler(timer2, ^{vector2(timer2);});

    // Set block for dispatch source when cancel source
    dispatch_source_set_cancel_handler(timer1, ^{
        dispatch_release(timer1);
        dispatch_release(queue);
        printf("end\n");
        exit(0);
    });
    dispatch_source_set_cancel_handler(timer2, ^{
        dispatch_release(timer2);
        dispatch_release(queue);
        printf("end\n");
        exit(0);
    }); 

    dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC); // after 1 sec

    // Set timer
    dispatch_source_set_timer(timer1, start, NSEC_PER_SEC / 5, 0);  // 0.2 sec
    dispatch_source_set_timer(timer2, start, NSEC_PER_SEC / 2, 0);  // 0.5 sec
    printf("start\n");    
    dispatch_resume(timer1);
    dispatch_resume(timer2);
    while(1)
    {
        ;;
    }
    return 0;
}