title: JSON text did not start with array or object and option to allow fragments not set not getting the response
body: <p>when i am going to convert the currency using xe currency converter api but not getting the response</p>
  
  <p>The expected response should be like </p>
  
  <blockquote>
    <p>{"terms":"<a href="http://www.xe.com/legal/dfs.php" rel="nofollow">http://www.xe.com/legal/dfs.php</a>","privacy":"<a href="http://www.xe.com/privacy.php" rel="nofollow">http://www.xe.com/privacy.php</a>","from":"USD","amount":1.0,"timestamp":"2016-03-18T06:22:00Z","to":[{"quotecurrency":"INR","mid":66.6094587811}]}</p>
  </blockquote>
  
  <p>i am getting the below error in response: </p>
  
  <blockquote>
    <p>Error: Error Domain=NSCocoaErrorDomain Code=3840 "JSON text did not start with array or object and option to allow fragments not set." UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set., NSUnderlyingError=0x7fa879f70190 {Error Domain=AFNetworkingErrorDomain Code=-1011 "Request failed: not found (404)" UserInfo= –<br>
    {AFNetworkingOperationFailingURLResponseErrorKey= { URL: xecdapi.xe.com/v1/convert_from? } { status code: 404, headers { Connection = "keep-alive"; "Content-Length" = 9; "Content-Type" = "text/plain; charset=utf-8"; } }, NSLocalizedDescription=Request failed: not found (404), NSErrorFailingURLKey=xecdapi.xe.com/v1/convert_from?}}}</p>
  </blockquote>
  
  <p>my code is:</p>
  
  <pre><code>AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
  manager.responseSerializer = [AFJSONResponseSerializer serializer];
  AFJSONResponseSerializer *jsonResponseSerializer = [AFJSONResponseSerializer serializer];
  NSMutableSet *jsonAcceptableContentTypes = [NSMutableSet setWithSet:jsonResponseSerializer.acceptableContentTypes];
  [jsonAcceptableContentTypes addObject:@"text/plain"];
  jsonResponseSerializer.acceptableContentTypes = jsonAcceptableContentTypes;
  manager.responseSerializer = jsonResponseSerializer;
  [manager.requestSerializer setValue:@“xxxxxxxxninternationalfze988134762" forHTTPHeaderField:@"User Name"];
  [manager.requestSerializer setValue:@“xxxxqngksq5nuqmmf7tjgcihak" forHTTPHeaderField:@"Password"];
  NSMutableDictionary *params = [[NSMutableDictionary alloc]init];
  [params setObject:@"USD" forKey:@"from"];
  [params setObject:@"INR" forKey:@"to"]; 
  </code></pre>