AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.requestSerializer = [AFgzipRequestSerializer serializerWithSerializer:[AFJSONRequestSerializer serializer]];

[manager POST:@"http://example.com/"
   parameters:@{@"foo": @"bar"}
      success:^(NSURLSessionDataTask *task, id responseObject) {
        NSLog(@"%@", responseObject);
}
      failure:^(NSURLSessionDataTask *task, NSError *error) {
        NSLog(@"[Error] %@", error);
}];