如何使用iOS 5 Twitter Framework发送直接消息？

class ViewController: UIViewController, TWTweetComposeViewControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        if let tweetComposeViewController = TWTweetComposeViewController(delegate: self, cancelButtonTitle: "Cancel", image: UIImage(named: "twitterIcon")) {
            view.addSubview(tweetComposeViewController.view)
            tweetComposeViewController.modalTransitionStyle = .coverVertical
            tweetComposeViewController.modalPresentationStyle = .fullScreen
        }
    }

    func tweetComposeViewControllerDidFinish(_ tweetComposeViewController: TWTweetComposeViewController) {
        tweetComposeViewController.dismiss(animated: true, completion: nil)
    }

    func sendDirectMessage(sender: AnyObject, message: String) {
        if let tweetVC = sender as? TWTweetComposeViewController {
            tweetVC.sendTweet(message)
        }
    }
}