GCD 队列笔记

// 异步函数 + 主队列
// 不会开启子线程 , 所有的任务在主线程中串行执行
- (void)async_main
{
    //1.创建队列
    dispatch_queue_t queue = dispatch_get_main_queue();
    //2.封装任务,把任务添加到队列
    dispatch_async(queue, ^{
        NSLog(@"1----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"2----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"3----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"4----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"5----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"6----%@",[NSThread currentThread]);
    });
}

---

// 同步函数 + 串行队列
// 不会开启子线程 , 所有的任务在当前线程中串行执行
- (void)sync_serial
{
    //1.创建队列
    dispatch_queue_t queue = dispatch_queue_create("com.ylink.www", DISPATCH_QUEUE_SERIAL);
    //2.封装任务,把任务添加到队列
    dispatch_sync(queue, ^{
        NSLog(@"1----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"2----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"3----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"4----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"5----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"6----%@",[NSThread currentThread]);
    });
}

---

// 同步函数 + 并发队列
// 不会创建子线程 , 所有任务都在(注意:当前)线程中串行执行
- (void)sync_Concurrent
{
    //1.创建队列
    dispatch_queue_t queue = dispatch_queue_create("com.ylink.www", DISPATCH_QUEUE_CONCURRENT);
    //2.封装任务,把任务添加到队列
    dispatch_sync(queue, ^{
        NSLog(@"1----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"2----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"3----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"4----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"5----%@",[NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"6----%@",[NSThread currentThread]);
    });
}

---

// 异步函数 + 串行队列
// 会创建一个子线程 , 所有任务都在该子线程中串行执行
- (void)asyn_serial
{
    //1.创建队列
    dispatch_queue_t queue = dispatch_queue_create("com.ylink.www", DISPATCH_QUEUE_SERIAL);
    //2.封装任务,把任务添加到队列
    dispatch_async(queue, ^{
        NSLog(@"1----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"2----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"3----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"4----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"5----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"6----%@",[NSThread currentThread]);
    });
}

---

// 异步函数 + 并发队列
// 创建的线程数不一定完全跟任务数一样多 , 线程数量系统自动决定
- (void)asy_Concurrent
{
    //1.创建并发队列
    dispatch_queue_t queue = dispatch_queue_create("com.ylink.www", DISPATCH_QUEUE_CONCURRENT);
    //2.封装任务,把任务添加到队列
    dispatch_async(queue, ^{
        NSLog(@"1----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"2----%@",[NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"3----%@",[NSThread currentThread]);
    });
}

快速迭代函数:

用的时候永远传并发队列就行
使用方法

栅栏函数:

队列组:

等所有的并发任务执行完才执行xxx任务

单个队列 多个队列
多个队列

老用法(不推荐):

老办法下载两张图片,下载完之后合成一张图片.

对应的函数方法:
区别:
一个任务通过block执行
一个任务通过函数执行

GCD注意事项: