title: How to specify tags when uploading video to Facebook using the Graph API
body: <p>I'm able to upload videos to Facebook successfully using the latest Graph API via Objective-C. However, I'd like to also tag certain Facebook users who are in the video. I cannot get this to work.</p>
  
  <p>The <a href="http://developers.facebook.com/docs/reference/api/video/" rel="nofollow">FB documentation</a> says that there is a "tag" field that accepts an array of objects containing id and name fields. However, if I try to pass a JSON string in this format the video upload fails, without any useful error message. Am I passing the tags data correctly?</p>
  
  <p>Here's sample code that fails. The code succeeds when I remove the @"tags" field from params, or set tagStr to an empty array, i.e. @"[]".</p>
  
  <pre><code>NSString *tagStr = @"[{\"id\":\"&lt;id-removed&gt;\", \"name\":\"&lt;name-removed&gt;\"}]";
  NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                data, @"video.mov",
                                @"video/quicktime", @"contentType",
                                titleStr, @"title",
                                descStr, @"description",
                                tagStr, @"tags",          // specifying tags fails
                                nil];
  
  [facebook requestWithGraphPath:@"me/videos"
                       andParams:params
                   andHttpMethod:@"POST"
                     andDelegate:self];
  </code></pre>