MFMessageComposeViewController在xcode 10.0 beta中不可用

Question

我正在使用此代码在ios 12.0中发送短信，但MFMessageComposeViewController在xcode 10.0 beta中对我不可用

func sendSMSText(phoneNumber: String) {
    if (MFMessageComposeViewController.canSendText()) {
        let controller = MFMessageComposeViewController()
        controller.body = ""
        controller.recipients = [phoneNumber]
        controller.messageComposeDelegate = self
        self.present(controller, animated: true, completion: nil)
    }
}

func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
    //... handle sms screen actions
    self.dismiss(animated: true, completion: nil)
}