问从iOS应用程序通过Facebook SDK向朋友发送消息

EN

class ViewController: UIViewController, FBSDKLoginButtonDelegate {

var currentUserIDString : String?

override func viewDidLoad() {
    super.viewDidLoad()

    let facebookLoginButton = FBSDKLoginButton()
    facebookLoginButton.delegate = self
    facebookLoginButton.center = self.view.center
    self.view.addSubview(facebookLoginButton)

    let button : UIButton = FBSDKMessengerShareButton.circularButtonWithStyle(FBSDKMessengerShareButtonStyle.Blue, width: 80)
    button.addTarget(self, action: "shareTest", forControlEvents: UIControlEvents.TouchUpInside)
    button.frame = CGRectMake(self.view.frame.size.width/2 - 40, 390, 80, 80)
    self.view.addSubview(button)

}

// other methods

}

func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) {


    let graphRequest = FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, gender, email"])

    graphRequest.startWithCompletionHandler { (connection, result, error) -> Void in

        if error != nil {
            print(error.localizedDescription)
        }

        else if let result = result {

            self.currentUserIDString = result["id"] as? String
            print(self.currentUserIDString)

        }
    }

}

func shareTestGraphRequest() {

    if FBSDKAccessToken.currentAccessToken() != nil {

        if FBSDKAccessToken.currentAccessToken().hasGranted("read_page_mailbox") {

            //establish param dictionary here
            let parameterDictionary = NSMutableDictionary()
            parameterDictionary.setObject("This is a test message, I'm building an app!", forKey: "message")
            parameterDictionary.setObject(self.currentUserIDString!, forKey: "from")
            parameterDictionary.setObject([], forKey: "to")

            let graphRequest = FBSDKGraphRequest.init(graphPath: "/{message-id}", parameters: parameterDictionary as [NSObject : AnyObject], HTTPMethod: "POST")

            graphRequest.startWithCompletionHandler { (connection, result, error) -> Void in


            }

        }
    }

    else {

        let loginManager = FBSDKLoginManager()
        loginManager.logInWithPublishPermissions(["read_page_mailbox"], fromViewController: self, handler: { (result, error) -> Void in

            if error != nil {
                print(error)
            }

            else if let result = result {
                print(result)

            }
        })
    }
}