异步队列同步的几种方式

异步队列同步的几种方式

 #pragma mark ---- dispatch_barrier_async
dispatch_queue_t queue = dispatch_queue_create("yohans.queue", DISPATCH_QUEUE_CONCURRENT);

dispatch_async(queue, ^{
    sleep(1);
    NSLog(@"get City");
});

dispatch_async(queue, ^{
    sleep(2);
    NSLog(@"get Category");
});

dispatch_barrier_async(queue, ^{
    NSLog(@"get Goods by City and Category");
});

#pragma mark ---- dispatch_group_notify
dispatch_group_t group = dispatch_group_create();

dispatch_group_async(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    sleep(1);
    NSLog(@"get City");
});

dispatch_group_async(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    sleep(2);
    NSLog(@"get Category");
});

dispatch_group_notify(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSLog(@"get Goods by City and Category");
});

#pragma mark ---- dispatch_group_notify 手工管理
dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    sleep(1);
    NSLog(@"get City");
    dispatch_group_leave(group);
});

dispatch_group_enter(group);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    sleep(2);
    NSLog(@"get Category");
    dispatch_group_leave(group);
});

dispatch_group_notify(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSLog(@"get Goods by City and Category");
});