Question

由于NSURLConnection被撤销，我需要转移到NSURLSession。我有一个URL和一些我需要输入的数据作为JSON。然后结果应该是JSON回来。我看到类似的东西：

NSError *error;

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
NSURL *url = [NSURL URLWithString:@"[JSON SERVER"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:60.0];

[request addValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request addValue:@"application/json" forHTTPHeaderField:@"Accept"];

[request setHTTPMethod:@"POST"];
NSDictionary *mapData = [[NSDictionary alloc] initWithObjectsAndKeys: @"TEST IOS", @"name",
                     @"IOS TYPE", @"typemap",
                     nil];
NSData *postData = [NSJSONSerialization dataWithJSONObject:mapData options:0 error:&error];
[request setHTTPBody:postData];


NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

}];

[postDataTask resume];

我这是正确的方法吗？

我的要求是： 1.将我的键值对转换为JSON。 2.将URL和JSON传递给可重用的函数。 3.获取返回的JSON数据。 4.解析返回的JSON数据。

Answer 1

您希望方法的调用者提供一个完成处理程序，它可以处理返回的数据或更新UI以指示完成。

就像SDK一样，您可以执行以下操作。假设我们调用函数makeRequest并且它需要一个参数作为请求的一部分发送。声明这样的方法：

- (void)makeRequest:(NSString *)param completion:(void (^)(NSDictionary *, NSError *))completion;

像这样实施：

- (void)makeRequest:(NSString *)param
         completion:(void (^)(NSDictionary *, NSError *))completion {

    // your OP code goes here, e.g.
    NSError *error;
    NSURLSessionConfiguration *configuration = // and so on

    // use the param to form the request if it needs one, then...

    NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request 
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        // here, we must abide by the interface of our completion handler.
        // we must call in EVERY code path, so the caller is never left waiting
        if (!error) {
            // convert the NSData response to a dictionary
            NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
            if (error) {
                // there was a parse error...maybe log it here, too
                completion(nil, error);
            } else {
                // success!
                completion(dictionary, nil);
            }
        } else {
            // error from the session...maybe log it here, too
            completion(nil, error);
        }
    }];
    [postDataTask resume];
}

调用此方法的代码如下所示：

// update the UI here to say "I'm busy making a request"
// call your function, which you've given a completion handler
[self makeRequest:@"someParam" completion:^(NSDictionary *someResult, NSError *error) {
    // here, update the UI to say "Not busy anymore"
    if (!error) {
        // update the model, which should cause views that depend on the model to update
        // e.g. [self.someUITableView reloadData];
    } else {
        // update UI to indicate error or take remedial action
    }
}];

注意以下几点：（1）返回类型为void，调用者期望从此方法返回任何内容，并且在调用它时不进行任何赋值。数据＆＃34;返回＆＃34;作为完成处理程序的参数提供，稍后在asnych请求完成后调用，（2）完成处理程序的签名完全匹配调用者在完成块^(NSDictionary *, NSError *)中声明的内容，这只是一个建议，典型的网络请求。

Answer 2

实例化NSURLSession和NSMutableURLRequest对象：

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setHTTPMethod:@"POST"];
[request addValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request addValue:@"application/json" forHTTPHeaderField:@"Accept"];

将您的键值对转换为JSON：

// choose the right type for your value.
NSDictionary *postDict = @{@"key1": value1, @"key2": value2};
NSData *postData = [NSJSONSerialization dataWithJSONObject:postDict options:0 error:nil];

使用URL和JSON进行POST：

[request setURL:[NSURL URLWithString:@"JSON SERVER"];
[request setHTTPBody:postData];
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

}];
[postDataTask resume];

解析在上面的completionHandler 中返回的：

if (!error) { NSDictionary *responseDict = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil]; } else { // error code here }

responseDict是已解析的数据。例如，如果服务器返回

{ "message":"Your messsage", "data1":value1, "data2":value2 }

您可以使用
轻松获取data1的值
[responseDict objectForKey:@"data1"];

如果您想使用不同的URL或JSON进行另一次POST，请重复步骤2-4的流程。

希望我的回答有所帮助。

使用JSON通过POST从NSURLSession获取数据

2 个答案: