Compose message and present MFMessageComposeViewController

MessageComposer.swift

import Foundation
import MessageUI

class MessageComposer: NSObject, MFMessageComposeViewControllerDelegate {
    
    var reciepient: String?
    var message: String?
    weak var alertPresenter: UIViewController?
    
    convenience init(reciepient: String?, message: String?, alertPresenter: UIViewController? = nil) {
        self.init()
        self.reciepient = reciepient
        self.message = message
        self.alertPresenter = alertPresenter
    }
    
    var canSendMessage: Bool {
        return MFMessageComposeViewController.canSendText()
    }
    
    var composedViewController: MFMessageComposeViewController? {
        guard canSendMessage else {
            print("Application can not send text, so returning...")
            self.showAlert()
            return nil
        }
        guard let reciepient = self.reciepient, reciepient.isValidPhoneNumber else {
            print("Phone number is not available")
            self.showReciepientAlert()
            return nil
        }
        let controller = MFMessageComposeViewController()
        controller.messageComposeDelegate = self
        controller.recipients = [reciepient]
        controller.body = message
        return controller
    }
    
    func showAlert() {
        let alert = UIAlertController.alert(
            title: "Cannot Send Message",
            message: "Text messaging is not available on this device. Please check the settings on your device.",
            action: .cancel())
        self.alertPresenter?.showAlert(alert)
    }
    
    func showReciepientAlert() {
        let alert = UIAlertController.alert(title: "Phone number isn't available", message: nil, action: .cancel())
        self.alertPresenter?.showAlert(alert)
    }
    
    func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
        controller.dismiss(animated: true, completion: nil)
    }
    
}