GCD汇总

//总结如下：
//1.同步请求：不会开启新的线程
//1-1.同步请求--串行队列：不开启新线程--按照顺序执行下去
//1-2.同步请求--并发列队：不开启新线程--按照顺序执行下去

//2.异步请求：会开启新的线程
//2-1.异步请求--串行队列：开启一条新线程--按照顺序执行下去
//2-2.异步请求--并发队列：每条请求开启一条新线程--无顺序执行

//3.主线程
//主线程上面的请求都会在主线程上面执行
//3-1.异步请求：在主线程上面不会开启新的线程--按照顺序执行下去
//3-2.同步请求：卡死  当触发同步请求的时候会立即触发这个方法，但是上面的方法还需要往下面走，相互之间卡死了。

- (void)viewDidLoad {
    [super viewDidLoad];

    [self test8];

}
//   <NSThread: 0x7fd2c3c088a0>{number = 1, name = main}
// 2><NSThread: 0x7fd2c3c14280>{number = 2, name = (null)}
// 4><NSThread: 0x7fd2c3c9a6a0>{number = 4, name = (null)}
// 3><NSThread: 0x7fd2c3e0c4b0>{number = 3, name = (null)}
// 1><NSThread: 0x7fd2c3e0d570>{number = 5, name = (null)}
// 5><NSThread: 0x7fd2c3c14280>{number = 2, name = (null)}
//异步队列--异步请求
//会创建新的线程--线程之间的执行时是并发的
-(void)test1{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    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]);
    });
}

//结果如下
//   <NSThread: 0x7fd5bac04910>{number = 1, name = main}
// 1><NSThread: 0x7fd5bac04910>{number = 1, name = main}
// 2><NSThread: 0x7fd5bac04910>{number = 1, name = main}
// 3><NSThread: 0x7fd5bac04910>{number = 1, name = main}
// 4><NSThread: 0x7fd5bac04910>{number = 1, name = main}
// 5><NSThread: 0x7fd5bac04910>{number = 1, name = main}
//异步队列--同步请求
//并没有开启新的线程--还是在主线程上面串行的执行
-(void)test2{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    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]);
    });
}

//结果如下
//   <NSThread: 0x7fed50d07b50>{number = 1, name = main}
// 1><NSThread: 0x7fed50d07b50>{number = 1, name = main}
// 2><NSThread: 0x7fed50d07b50>{number = 1, name = main}
// 3><NSThread: 0x7fed50d07b50>{number = 1, name = main}
// 4><NSThread: 0x7fed50d07b50>{number = 1, name = main}
// 5><NSThread: 0x7fed50d07b50>{number = 1, name = main}
//串行队列--同步请求
//并没有开启新的线程--还是在主线程上面串行的执行
-(void)test3{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_queue_create("test", DISPATCH_QUEUE_SERIAL);
    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]);
    });
}

//结果如下
//   <NSThread: 0x7faa8a606430>{number = 1, name = main}
// 1><NSThread: 0x7faa8a61e880>{number = 2, name = (null)}
// 2><NSThread: 0x7faa8a61e880>{number = 2, name = (null)}
// 3><NSThread: 0x7faa8a61e880>{number = 2, name = (null)}
// 4><NSThread: 0x7faa8a61e880>{number = 2, name = (null)}
// 5><NSThread: 0x7faa8a61e880>{number = 2, name = (null)}
//串行队列--异步请求
//开启了一条新的线程--按照顺序执行
-(void)test4{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_queue_create("test", DISPATCH_QUEUE_SERIAL);
    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]);
    });
}

//结果如下
//   <NSThread: 0x7fe849c048f0>{number = 1, name = main}
// 1><NSThread: 0x7fe849c048f0>{number = 1, name = main}
// 2><NSThread: 0x7fe849c048f0>{number = 1, name = main}
// 3><NSThread: 0x7fe849c048f0>{number = 1, name = main}
// 4><NSThread: 0x7fe849c048f0>{number = 1, name = main}
// 5><NSThread: 0x7fe849c048f0>{number = 1, name = main}
//主线程--异步请求
//不会开启新的线程，都是在主线程上面执行的
-(void)test5{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_get_main_queue();
    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]);
    });
}

//结果如下
// <NSThread: 0x7fe881501cc0>{number = 1, name = main}
//主线程--同步请求
//卡主线程
-(void)test6{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_get_main_queue();
    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]);
    });
}

//结果如下
//   <NSThread: 0x7fc70a7023c0>{number = 1, name = main}
// 2><NSThread: 0x7fc70a443ac0>{number = 2, name = (null)}
// 3><NSThread: 0x7fc70a61a740>{number = 4, name = (null)}
// 1><NSThread: 0x7fc70a70ea60>{number = 3, name = (null)}
// done

//开启多条线程
//统一完成后

-(void)test7{

    NSLog(@"%@",[NSThread currentThread]);

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_async(group, queue, ^{
        NSLog(@"1>%@",[NSThread currentThread]);
    });

    dispatch_group_async(group, queue, ^{
       NSLog(@"2>%@",[NSThread currentThread]);
    });

    dispatch_group_async(group, queue, ^{
        NSLog(@"3>%@",[NSThread currentThread]);
    });

    dispatch_group_notify(group, queue, ^{
        NSLog(@"done");
    });
}