dispatch_group_t 异步并发请求网络

一个操作是 需要同时并发 5个网络异步请求，然后最后当网络都全部请求完成后，再刷新UI

dispatch_queue_t concurrentQueue = dispatch_queue_create("test1", DISPATCH_QUEUE_CONCURRENT);
    dispatch_group_t group = dispatch_group_create();
    for (int i = 0; i < 5; i++) {
        dispatch_group_async(group, concurrentQueue, ^{
            NSLog(@"开始--%d",i);
            dispatch_group_enter(group);
            LoginRequest *request = [[LoginRequest alloc]initWithLoginMobile:@"123" password:@"123" method:HTTPMethodGet];
            [[NetworkCenter sharedInstance] startRequestWith:request completion:^(id  _Nullable result, NSString * _Nullable error) {
                dispatch_group_leave(group);
                NSLog(@"结束--%d",i);
            }];
            NSLog(@"过程中--%d",i);
        });
    }
    dispatch_group_notify(group, concurrentQueue, ^{
        NSLog(@"全部结束-刷新UI");
    });

结果

2021-04-08 17:07:04.142538+0800 ws[2172:1065286] 开始--0
2021-04-08 17:07:04.142723+0800 ws[2172:1065286] (null)
2021-04-08 17:07:04.142853+0800 ws[2172:1065162] 开始--1
2021-04-08 17:07:04.142956+0800 ws[2172:1065162] (null)
2021-04-08 17:07:04.142965+0800 ws[2172:1065296] 开始--2
2021-04-08 17:07:04.143031+0800 ws[2172:1065296] (null)
2021-04-08 17:07:04.143189+0800 ws[2172:1065298] 开始--3
2021-04-08 17:07:04.143255+0800 ws[2172:1065298] (null)
2021-04-08 17:07:04.143298+0800 ws[2172:1065374] 开始--4
2021-04-08 17:07:04.143678+0800 ws[2172:1065374] (null)
2021-04-08 17:07:04.144462+0800 ws[2172:1065162] 过程中--1
2021-04-08 17:07:04.144464+0800 ws[2172:1065296] 过程中--2
2021-04-08 17:07:04.144738+0800 ws[2172:1065298] 过程中--3
2021-04-08 17:07:04.145017+0800 ws[2172:1065374] 过程中--4
2021-04-08 17:07:04.145248+0800 ws[2172:1065286] 过程中--0
2021-04-08 17:07:04.406002+0800 ws[2172:1064910] 结束--3
2021-04-08 17:07:04.406988+0800 ws[2172:1064910] 结束--2
2021-04-08 17:07:04.408535+0800 ws[2172:1064910] 结束--1
2021-04-08 17:07:04.410091+0800 ws[2172:1064910] 结束--4
2021-04-08 17:07:04.457578+0800 ws[2172:1064910] 结束--0
2021-04-08 17:07:04.457588+0800 ws[2172:1065286] 全部结束-刷新UI