Facebook iOS SDK: Post on my wall with mention friends

Question

I would like to make post with an image, message and mention some friends. I'm posting photo using Graph API

[FBRequestConnection startWithGraphPath:@"me/photos" parameters:dictionary HTTPMethod:@"POST" completionHandler:

and got friends list using

[FBRequestConnection startWithGraphPath:@"/me/taggable_friends"
                                              parameters:nil
                                              HTTPMethod:@"GET"
                                       completionHandler:

every friend has an id like this "AaJIwZcI7HgWAY1FXkqc5AMjIzE3k8TEuv9YligJRa_2M1EmZ3iGvFZxRpF6s1eW3pCNKep2RUxy5KWH3WgOSUH3QSRLH_RRaTlfgcFjRX9DpQ" but how implement this id in message?
I have used different ways but nothing:
https://developers.facebook.com/docs/opengraph/using-actions/v2.1#people

[dictionary setObject:array forKey:@"tags"];
[dictionary setObject:[NSString stringWithFormat:@"@[%@:1:%@]",userID,userName]forKey:@"message"];

Any idea or something that help?

Answer 1

Mentioning friends may looks pretty easy, but in fact it is really complicated thing worth big tutorial and involving a lot of steps to be done and api requests to be performed. To do this you should create object and do some action with it. As for terminology:object consists of generic data such as type, image, title, url, custom fields, etc. action consists of object and can also mention friends. Thus:

1. You should create custom story on your app's page in section "open graph" or use existing one from here. Since now assume we create custom story.
2. You should perform request to create object. You can get sample requests from your app's page in section "open graph" by clicking "get code" button on the right of story. Those request for http (not for ios in particular) but show all necessary fileds that must be filled in to perform requests successfully.
3. Than upload some image(s) and keep their urls (how to upload photo into Facebook note:it doesn't get you url and you need to retrieve it using simple get request. i know it is stupid but unfortunately the only way to get url from photo posted just a second ago).

4. Get taggable friends and keep their pseudo-ids.

5. Perform request for action. It is the place where all magic is done. Perform request with necessary fields: "image", "tags" and, probably "fb:explicitly_shared" (obviously set to true). Note that "image" is array, "tags" are comma-separated values, "fb:explicitly_shared" is boolean value. From the ios perspective request could look like this:

   [FBRequestConnection startWithGraphPath:[NSString stringWithFormat:@"me/%@", kFBActionNameFull]
                                      parameters:@{kFBObjectNameShort:objectId,
                                                   @"fb:explicitly_shared":@"true",
                                                   @"tags":@"friend1_tag,friend2_tag",
                                                   @"image":@[@{@"image":@"some_url",
                                                                @"user_generated":@"true"}]}
                                      HTTPMethod:@"POST"
                               completionHandler: ...]

After all this steps you could see story on your page.

As you can see mentioning friends is very difficult task, requiring a lot of time to implement. I could add some code to explanation above, but without deep understanding of stories mechanism you can not successfully post image and tag friends

And yes, you must

6. Send your app with story and all requested permissions to submission

in order to use your app into production.