Ios afp后值

我的问题是：

NSDictionary *parameters = @{@"type": @"5", @"xq": @"a", @"apid": @"b", @"apsecret": @"c", @"astoken": @"d"};

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
manager.responseSerializer = [AFJSONResponseSerializer serializer]; manager.requestSerializer = [AFJSONRequestSerializer serializer];

[manager.requestSerializer setValue:[NSString stringWithFormat:@"text/plain; charset=UTF-8"] forHTTPHeaderField:@"Content-Type"]; 

如果我使用GET：

[manager GET:@"http://127.0.0.1/123.php" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {   
NSLog(@"responseObject : %@", responseObject);
 } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
     NSLog(@"error : %@", error);
 }];

我可以获得$\u get['parameters']值

但当我使用POST时：

[manager POST:@"http://127.0.0.1/123.php" parameters:parameters 
      success:^(AFHTTPRequestOperation *operation, id responseObject) 
{ 
   NSLog(@"responseObject : %@", responseObject); 
}     failure:^(AFHTTPRequestOperation *operation, NSError *error) 
{ 
   NSLog(@"error : %@", error); 
}];

我总是得到$\u POST['parameters']值为null

---

我在设置中做错了什么吗？

将第一个代码段的第四行更改为

[manager.requestSerializer setValue:[AFJSONRequestSerializer serializer]];

很抱歉

我发现它可以工作

AFHTTPSessionManager *manager = [[AFHTTPSessionManager alloc] initWithBaseURL:[NSURL URLWithString:@"http://127.0.0.1/123.php"]];
manager.responseSerializer = [AFJSONResponseSerializer serializer];

[manager POST:@"123.php"
   parameters:parameters
      success:^(NSURLSessionDataTask *task, id responseObject) {
          NSLog(@"responseObject : %@", responseObject);
      } failure:^(NSURLSessionDataTask *task, NSError *error) {
           NSLog(@"error : %@", error);
      }];

---

Xcode说：“AFHTTPRequestSerializer”没有可见的@interface声明选择器“setValue:”，那么您是如何在没有错误的情况下使用原始代码设置值的？