iOS 并发图片上传，顺序获得ImageUrl数组

-(void)uploadImage{
    _saveBtn.userInteractionEnabled=NO;
      // 图片imagrUrl 站位
    
    [_selectedPhotos enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        [_imageIdArray addObject:[NSNull null]];
    }];
    
    dispatch_group_t group = dispatch_group_create();
    [_selectedPhotos enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        // 进入线程组
        dispatch_group_enter(group);
        // 开启线程
        dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            
            NSString *url = [NSString stringWithFormat:@"%@",upLoadImgUrl];
            NSString *userId = [NSString stringWithFormat:@"%@",[AppData share].userid];
            NSDictionary *params = @{@"userid":userId,
                                     @"type":@"12",
                                     @"data":_selectedPhotos[idx]
                                     };
            NSString *token = [[NSUserDefaults standardUserDefaults] valueForKey:TOKEN];
            NSString *aa = [NSString stringWithFormat:@"Bearer %@",token];
            NSDictionary *headerDic = @{@"userid":userId,@"Authorization":aa};
            UIImage *loadImg = _selectedPhotos[idx];
            NSData *loadImgData = UIImageJPEGRepresentation(loadImg, 0.05);
            [NTNetUtil uploadRequestWithUrl:url requestHeader:headerDic method:requestPOST parameters:params data:loadImgData block:^(NTHttpRequest *networkRequest, NSError *error) {
                if (error == nil)
                {
                    NSDictionary *responseDic = (NSDictionary *)networkRequest.responseData;
                    NSDictionary *dic = [NSDictionary dictionary];
                    NSString *r = [NSString stringWithFormat:@"%@",[responseDic objectForKey:@"success"]];
                    if ([r isEqualToString:@"1"]) {
                        dic = [responseDic objectForKey:@"data"];
                        NSString *imgUrl = [NSString stringWithFormat:@"%@",[dic objectForKey:@"url"]];
                        // 添加图片
                        @synchronized (self.imageIdArray)
                        { // NSMutableArray 是线程不安全的，所以加个同步锁
                            [self.imageIdArray replaceObjectAtIndex:idx withObject:imgUrl];
                            NSLog(@"-----------  图片index-%ld 上传 ",idx);
                        }
                    }else {
                        
                    }
                }else {
                    
                }
                // 离开线程组
                dispatch_group_leave(group);
            }];
        });
    }];
    
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"-----------  图片完成!");
        for (NSString * response in self.imageIdArray) {
            NSLog(@" 图片-- %@", response);
        }
        
        [self serialByGroupWait];
    });
    
}