Question

我正在尝试聚合来自多个同时运行的NSURLSessionDataTasks的数据。

__block NSMutableDictionary *languageDetails = [NSMutableDictionary new];
[repos enumerateObjectsUsingBlock:^(NSDictionary *repoDict, NSUInteger idx, BOOL * _Nonnull stop) {
    NSString *languageUrl = repoDict[@"languages_url"];
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:languageUrl]
                                                             completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
                                                                 // JSON Parse response
                                                                 // Update languageDetails
                                                             }];
    [task resume];
}];

如何在完成所有数据任务后调用主回调或委托来设置它？

Answer 1

您可以使用调度组来收听所有通话结束时的信息：

dispatch_group_t tasks = dispatch_group_create();

__block NSMutableDictionary *languageDetails = [NSMutableDictionary new];
[repos enumerateObjectsUsingBlock:^(NSDictionary *repoDict, NSUInteger idx, BOOL * _Nonnull stop) {
    dispatch_group_enter(tasks);

    NSString *languageUrl = repoDict[@"languages_url"];
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:languageUrl]
                                                             completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
                                                                 // JSON Parse response
                                                                 // Update languageDetails

                                                                 dispatch_group_leave(tasks);
                                                             }];
    [task resume];
}];

dispatch_group_notify(tasks, dispatch_get_main_queue(), ^{
    // All the tasks are done, do whatever
});

在每个dispatch_group_leave

发出dispatch_group_enter来电之前，通知功能块才会运行

如何聚合来自多个NSURLSessionDataTasks的响应？

1 个答案: