ios - Facebook Graph API iOS tag friend whit SLRequest

Question

I have a problem with facebook API. According to the documentation (https://developers.facebook.com/docs/reference/api/post/) of facebook you can tagging a friend whit:

"to": {
        "data": [
           {
              "name": "Facebook Name",
              "id": "XXXXXXXXXX_id"
           },
           {
              "name": "Facebook Name",
              "id": "XXXXXXXXXX_id"
           }
        ]
     }

To run the request I use SLRequest whit this code:

NSMutableDictionary *dictionaryMessage =[[NSMutableDictionary alloc]init];
NSURL *requestURL  = [NSURL URLWithString:@"https://graph.facebook.com/me/feed"];
if (message != nil) {
      [dictionaryMessage setObject:message forKey:@"message"];
  }
if (placeId !=nil) {
    [dictionaryMessage setObject:placeId forKey:@"place"];
}
if ([facebookFriendArray count]>0) {
    NSMutableArray *tagFriend = [[NSMutableArray alloc]initWithCapacity:[facebookFriendArray count]];
    for (TagPeople * friend in facebookFriendArray) {
        NSDictionary *userDic = [[NSDictionary alloc]initWithObjectsAndKeys:friend.idSocial,@"id",friend.nome,@"name", nil];
        [tagFriend addObject:userDic];
    }
    NSDictionary *dictionarySup = [[NSDictionary alloc]initWithObjectsAndKeys:tagFriend,@"data", nil];
    [dictionaryMessage setObject:dictionarySup forKey:@"to"];
}
SLRequest *postRequest = [SLRequest requestForServiceType:SLServiceTypeFacebook requestMethod:SLRequestMethodPOST
                                                      URL:requestURL parameters:jsonObject];

if (immagine != nil) {
    NSData *imageData = UIImageJPEGRepresentation(immagine, 0.5);
    [postRequest addMultipartData:imageData withName:@"images" type:@"multipart/jpeg" filename:@"file_name"];
}

postRequest.account = accountFacebook;

[postRequest performRequestWithHandler:^(NSData *responseData,
                                         NSHTTPURLResponse *urlResponse, NSError *error)
 {

But this code generate the error: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI length]: unrecognized selector sent to instance 0x1245efe0' ***. What is wrong? Thanks in advance for the answers. Sorry for my bad English