Crash after share by email or sms in iOS swift

I want to share some content. It my app crashes after I send email or sms. The emails and sms received. It works good with all other types. I added Social framework and imported Social to that class

My code:

    if let myWebsite = NSURL(string: "http://www.mstcode.com")
    {
        let messageStr = "Learn how to build iPhone apps"
        let shareItems = [messageStr, myWebsite]
        let activityController = UIActivityViewController(activityItems: shareItems, applicationActivities: nil)
        if UIDevice.currentDevice().userInterfaceIdiom == .Pad {
            activityController.popoverPresentationController?.sourceView = sender
        }
        self.presentViewController(activityController, animated: true,completion: nil)
    }