网络异步请求同步、顺序处理

一、异步网络请求按顺序请求（信号量）

dispatch_semaphore_t sem = dispatch_semaphore_create(1);
    dispatch_queue_t queue = dispatch_queue_create("testBlock", NULL);
    dispatch_async(queue, ^{
        dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
        [self.requestObj fetchHomeBannerDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----hahahahahah");
            dispatch_semaphore_signal(sem);
        }];
    });
    dispatch_async(queue, ^{
        dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
        [self.requestObj fetchGetAdvertisementCompletion:^(BOOL success) {
            NSLog(@"lililili ----babababababa");
            dispatch_semaphore_signal(sem);
        }];
    });
    dispatch_async(queue, ^{
        dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
        [self.requestObj fetchGetPropagandaInfo:^(BOOL success) {
            NSLog(@"lililili ----cacacacacaca");
            dispatch_semaphore_signal(sem);
        }];
       
    });
    dispatch_async(queue, ^{
        dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
        [self.requestObj fetchHomeRigsterDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----dadadadadada");
            dispatch_semaphore_signal(sem);
        }];
        
    });

打印结果

2018-09-03 17:36:57.714339+0800 xx[6989:1205370] lililili ----hahahahahah
2018-09-03 17:36:57.783999+0800 xx[6989:1205370] lililili ----babababababa
2018-09-03 17:36:57.912055+0800 xx[6989:1205370] lililili ----cacacacacaca
2018-09-03 17:36:58.027282+0800 xx[6989:1205370] lililili ----dadadadadada

二、多个网络异步请求最后同步（Group）

  dispatch_group_t dispatchGroup = dispatch_group_create();
    dispatch_queue_t queue = dispatch_queue_create("queue", DISPATCH_QUEUE_SERIAL);

    dispatch_group_enter(dispatchGroup);
    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchHomeBannerDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----hahahahahah");
            dispatch_group_leave(dispatchGroup);
        }];
    });
    
    dispatch_group_enter(dispatchGroup);
    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchGetAdvertisementCompletion:^(BOOL success) {
            NSLog(@"lililili ----babababababa");
            dispatch_group_leave(dispatchGroup);
        }];
    });
    
    dispatch_group_enter(dispatchGroup);
    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchGetPropagandaInfo:^(BOOL success) {
            NSLog(@"lililili ----cacacacacaca");
            dispatch_group_leave(dispatchGroup);
        }];
    });
    
    dispatch_group_enter(dispatchGroup);
    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchHomeRigsterDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----dadadadadada");
            dispatch_group_leave(dispatchGroup);
        }];
    });

    dispatch_group_notify(dispatchGroup, queue, ^{

        NSLog(@"请求完成");
    });

打印结果

2018-09-03 17:32:20.433136+0800 xx[6912:1183702] lililili ----babababababa
2018-09-03 17:32:20.439339+0800 xx[6912:1183702] lililili ----cacacacacaca
2018-09-03 17:32:20.440473+0800 xx[6912:1183702] lililili ----hahahahahah
2018-09-03 17:32:20.442021+0800 xx[6912:1183702] lililili ----dadadadadada
2018-09-03 17:32:20.442153+0800 xx[6912:1184110] 请求完成

三、多个网络异步请求最后同步(Group+信号量)

  dispatch_group_t dispatchGroup = dispatch_group_create();
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_semaphore_t dsema = dispatch_semaphore_create(0);
    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchHomeBannerDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----hahahahahah");
            dispatch_semaphore_signal(dsema);
        }];
        dispatch_semaphore_wait(dsema, DISPATCH_TIME_FOREVER);
    });

    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchGetAdvertisementCompletion:^(BOOL success) {
            NSLog(@"lililili ----babababababa");
            dispatch_semaphore_signal(dsema);
        }];
        dispatch_semaphore_wait(dsema, DISPATCH_TIME_FOREVER);
    });

    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchGetPropagandaInfo:^(BOOL success) {
            NSLog(@"lililili ----cacacacacaca");
            dispatch_semaphore_signal(dsema);
        }];
        dispatch_semaphore_wait(dsema, DISPATCH_TIME_FOREVER);
    });

    dispatch_group_async(dispatchGroup, queue, ^{
        [self.requestObj fetchHomeRigsterDataCompletion:^(BOOL success) {
            NSLog(@"lililili ----dadadadadada");
            dispatch_semaphore_signal(dsema);
        }];
        dispatch_semaphore_wait(dsema, DISPATCH_TIME_FOREVER);
    });

    dispatch_group_notify(dispatchGroup, queue, ^{

        NSLog(@"请求完成");
    });

打印结果

2018-09-03 17:51:16.829153+0800 xx[7329:1270405] lililili ----babababababa
2018-09-03 17:51:16.833271+0800 xx[7329:1270405] lililili ----dadadadadada
2018-09-03 17:51:16.835973+0800 xx[7329:1270405] lililili ----hahahahahah
2018-09-03 17:51:16.903278+0800 xx[7329:1270405] lililili ----cacacacacaca
2018-09-03 17:51:16.903525+0800 xx[7329:1270499] 请求完成

参考文章：

多个网络请求并发执行、顺序执行