MessageComposeViewController只呈现一次

Question

我正在使用Xcode 8为iPhone构建应用程序。
我的简单应用程序有一个按钮。 当用户点击此按钮时，将调用messageComposeViewController ，并填写电话号码和消息内容。
单击“发送”按钮后，该消息成功完成。

问题是MessageComposeViewController只显示一次。
发送消息后，当我点击按钮调用它时，会出现一个黑屏而不是消息编写器。

我的代码附在下面。
我感谢任何帮助。

import UIKit
import MessageUI

class ViewController: UIViewController, MFMessageComposeViewControllerDelegate   {

    let msg = MFMessageComposeViewController()

    @IBOutlet weak var coordinate_label: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }


    @IBAction func sendMessage(_ sender: AnyObject) {

        self.msg.body = "Message Content"
        self.msg.recipients = ["xxx-xxx-xxxx"]
        self.msg.messageComposeDelegate = self

        self.present(msg, animated: false, completion: nil)
    }

    func messageComposeViewController(_ controller:   MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
        switch result.rawValue {
            case MessageComposeResult.cancelled.rawValue:
                dismiss(animated: true, completion: nil)
            case MessageComposeResult.failed.rawValue:
                dismiss(animated: true, completion: nil)
            case MessageComposeResult.sent.rawValue:
                dismiss(animated: true, completion: nil)
            default:
                break;
        }
    }   
}

Answer 1

试试这个代码

import Foundation
import MessageUI

let textMessageRecipients = ["1-800-867-5309"] // for pre-populating the recipients list (optional, depending on your needs)

class MessageComposer: NSObject, MFMessageComposeViewControllerDelegate {

    // A wrapper function to indicate whether or not a text message can be sent from the user's device
    func canSendText() -> Bool {
        return MFMessageComposeViewController.canSendText()
    }

    // Configures and returns a MFMessageComposeViewController instance
    func configuredMessageComposeViewController() -> MFMessageComposeViewController {
        let messageComposeVC = MFMessageComposeViewController()
        messageComposeVC.messageComposeDelegate = self  //  Make sure to set this property to self, so that the controller can be dismissed!
        messageComposeVC.recipients = textMessageRecipients
        messageComposeVC.body = "Hey friend - Just sending a text message in-app using Swift!"
        return messageComposeVC
    }

    // MFMessageComposeViewControllerDelegate callback - dismisses the view controller when the user is finished with it
    func messageComposeViewController(controller: MFMessageComposeViewController!, didFinishWithResult result: MessageComposeResult) {
        controller.dismissViewControllerAnimated(true, completion: nil)
    }
}

注意，最新语法2017 ..

func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
    controller.dismiss(animated: true, completion: nil)
}

在你的viewController ..

import UIKit

class ViewController: UIViewController {
    // Create a MessageComposer
    let messageComposer = MessageComposer()

    @IBAction func sendTextMessageButtonTapped(sender: UIButton) {
        // Make sure the device can send text messages
        if (messageComposer.canSendText()) {
            // Obtain a configured MFMessageComposeViewController
            let messageComposeVC = messageComposer.configuredMessageComposeViewController()

            // Present the configured MFMessageComposeViewController instance
            // Note that the dismissal of the VC will be handled by the messageComposer instance,
            // since it implements the appropriate delegate call-back
            presentViewController(messageComposeVC, animated: true, completion: nil)
        } else {
            // Let the user know if his/her device isn't able to send text messages
            let errorAlert = UIAlertView(title: "Cannot Send Text Message", message: "Your device is not able to send text messages.", delegate: self, cancelButtonTitle: "OK")
            errorAlert.show()
        }
    }
}