串行启动 NSURLConnection 请求 [英] Start NSURLConnection requests serially

问题描述

我正在遍历一个包含几个字符串的数组，并为每个字符串向 Web 服务器发出请求数组中的字符串.

I'm looping through an array which contains few strings and making a request to a web server for each strings in the array.

我希望在将后续请求发送到服务器之前完全处理每个请求.因为每个请求都会向我发送一个响应，我将在下一个请求中发送该响应等等.

I would like each request to be processed completely before the subsequent request is sent to the server. Because each request sends me a response which I will send with next request and so on.

我遇到的问题是我的 NSURLConnection 是使用标准异步调用设置的.这导致请求不会阻塞任何后续请求.但是我需要在第一次完成之前阻止循环中的其他请求.

The problem I am having is that my NSURLConnection is set up using the standard asynchronous call. This results in requests not blocking any subsequent requests. But I need to block other requests in the loop before first completes.

请求 URL 始终相同，只有 JSON 数据随循环中的每个请求而变化.这是我的代码

The request URL is same always , only JSON data changes with every request in the loop. Here is my code

for (int i = 0; i < array.count; i++)
{


     NSData *jsonData = [NSJSONSerialization dataWithJSONObject:finalJSON options:NSJSONWritingPrettyPrinted error:&error];
     if (!jsonData) {
                NSLog(@"Error creating JSON object: %@", [error localizedDescription]);
            }


      NSString *url = [NSString stringWithFormat:@"abc.com/folders"];

      NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];

      [request setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
      [request setValue:APIKEY forHTTPHeaderField:@"X_API_KEY"];

      [request setHTTPMethod:@"POST"];
      [request setHTTPBody:jsonData];

            //I am adding all connections to NSDictionary so that later I can process request.
      NSURLConnection *connection = [self connectionForRequest:request];
      [connection start];                

}

推荐答案

我为你的问题想到了 2 个解决方案:

I thought of 2 solutions for your problem:

1. AFNetworking - 你可以使用 AFNetworking 并维护一个计数器在成功块中.计数器将对请求进行计数，当所有请求完成后，将执行您的下一个任务.

1. AFNetworking - U can use AFNetworking and maintain a counter in the success block. The counter will count the requests and when all done, will do your next task.

GCD - 调度组 - Grand Central Dispatch 为您提供创建组或请求并在最后(当所有请求完成时)做某事的选项.为此，你需要阅读很好的教程(Ray Wenderlich"的第二部分.如果你不熟悉 GCD，请跳到教程的第一部分).

GCD - Dispatch Groups - Grand Central Dispatch provide u the option to make group or requests and do something at the end (when all the requests finished). For that, u need to read nice tutorial (2nd part of "Ray Wenderlich". If U r not familiar with GCD, jump to the tutorial 1st part).

无论如何，使用上面的代码你无法完成你的任务.你没有任何在请求结束时运行的异步块.

Anyway, With your code above U can't achieve your task. U don't have any async block which run at the end of the requests.

使用 AFNetworking:

Use AFNetworking:

你必须先删除你的 for 循环，然后这样做:

U must remove your for loop first, and then do like this:

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
[manager POST:@"http://example.com/resources.json" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) { // HERE u can do your second request which uses the first response

        AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
        NSDictionary *parameters_new = <USE_YOUR_DATA_FROM_responseObject>;
        [manager POST:@"http://example.com/resources.json" parameters:parameters      success:^(AFHTTPRequestOperation *operation, id responseObject) { // HERE u can do your third request which uses the first and second response



        } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
             NSLog(@"Error: %@", error);
        }]; 


} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

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