title: How to tag users in a photo using the Facebook iOS SDK?
body: <p>I can't seem to work out how to tag users in a Facebook photo upload.</p>
  
  <p>The documentation seems to suggest that you use an array, but the following code doesn't parse correctly (causes an application crash)</p>
  
  <pre><code>- (void)uploadImage:(UIImage *)img
             withTags:(NSArray *)tags
  {
      NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                     @"msgstring", @"message",
                                     img, @"picture",  
                                     nil];
      if (tags) {
          [params setObject:tags
                     forKey:@"tags"];
      }
  
      self.requestType = FBAssistantRequestImageUpload;
  
      [self.facebook requestWithGraphPath:@"me/photos"
                                andParams:params
                            andHttpMethod:@"POST"
                              andDelegate:self];
  }
  </code></pre>
  
  <p>It works fine without the tags.  The array at the moment contains a single string with the identifier of the friend I wish to tag.</p>
  
  <p>I assume I'm adding the tags incorrectly.  I was hoping to avoid having to use the three-step method outlined here: <a href="https://stackoverflow.com/questions/8360353/tag-friends-in-facebook-photo-upload">Tag Friends in Facebook Photo Upload</a>, as I believe that requires photos permission, which just posting the photo doesn't need.</p>