消息不在FB上发布

Question

SLComposeViewController * controller = [SLComposeViewController composeViewControllerForServiceType：SLServiceTypeFacebook];

[controller setInitialText:kShareViaFacebookMessage];
[controller addURL: [NSURL URLWithString:kShareViaFacebookURL]];
[self presentViewController:controller animated:YES completion:Nil];

此代码中的问题是什么？为什么它没有在帖子上显示消息？