MFMailComposeViewController in Swift

问题

This is sample code:

import UIKit
import MessageUI

class ViewController: UIViewController, MFMailComposeViewControllerDelegate {

    @IBAction func showEmail(sender : AnyObject) {
        var emailTitle = "Test Email"
        var messageBody = "This is a test email body"
        var toRecipents = ["a.nakhimov@gmail.com"]
        var mc: MFMailComposeViewController = MFMailComposeViewController()
        mc.mailComposeDelegate = self
        mc.setSubject(emailTitle)
        mc.setMessageBody(messageBody, isHTML: false)
        mc.setToRecipients(toRecipents)

        self.presentViewController(mc, animated: true, completion: nil)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    func mailComposeController(controller:MFMailComposeViewController, didFinishWithResult result:MFMailComposeResult, error:NSError) {
        switch result {
        case MFMailComposeResultCancelled:
            NSLog("Mail cancelled")
        case MFMailComposeResultSaved:
            NSLog("Mail saved")
        case MFMailComposeResultSent:
            NSLog("Mail sent")
        case MFMailComposeResultFailed:
            NSLog("Mail sent failure: %@", [error.localizedDescription])
        default:
            break
        }
        self.dismissViewControllerAnimated(false, completion: nil)
    }
}

In function mailComposeController I get an error on every case expression:

Could not find an overload '~=' that accepts the supplied arguments.

What am I doing wrong?

回答1:

I compared MFMailComposeResult documentation on both Xcode 5 and Xcode 6. In Swift, MFMailComposeResult is a struct

struct MFMailComposeResult {
    init(_ value: CUnsignedInt) // available in iPhone 3.0
    var value: CUnsignedInt
}

with MFMailComposeResultCancelled as a constant of type MFMailComposeResult:

var MFMailComposeResultCancelled: MFMailComposeResult { get }

while it's an enum in Objective-C:

 enum MFMailComposeResult {
    MFMailComposeResultCancelled,
    MFMailComposeResultSaved,
    MFMailComposeResultSent,
    MFMailComposeResultFailed
};
typedef enum MFMailComposeResult MFMailComposeResult;   // available in iPhone 3.0

In order to make your code work, you will have to compare their values which are CUnsignedInt.

So you will have to type the following code:

func mailComposeController(controller:MFMailComposeViewController, didFinishWithResult result:MFMailComposeResult, error:NSError) {
    switch result.value {
    case MFMailComposeResultCancelled.value:
        println("Mail cancelled")
    case MFMailComposeResultSaved.value:
        println("Mail saved")
    case MFMailComposeResultSent.value:
        println("Mail sent")
    case MFMailComposeResultFailed.value:
        println("Mail sent failure: \(error.localizedDescription)")
    default:
        break
    }
    self.dismissViewControllerAnimated(false, completion: nil)
}

回答2:

in Swift 2.0 do this:

func mailComposeController(controller: MFMailComposeViewController, didFinishWithResult result: MFMailComposeResult, error: NSError?) {
        switch result.rawValue {
        case MFMailComposeResultCancelled.rawValue:
            print("Mail cancelled")
        case MFMailComposeResultSaved.rawValue:
            print("Mail saved")
        case MFMailComposeResultSent.rawValue:
            print("Mail sent")
        case MFMailComposeResultFailed.rawValue:
            print("Mail sent failure: \(error!.localizedDescription)")
        default:
            break
        }
        controller.dismissViewControllerAnimated(true, completion: nil)
    }

回答3:

In swift 3.0 -> Syntax Change

func mailComposeController(controller: MFMailComposeViewController,
                           didFinishWithResult result: MFMailComposeResult, error: NSError?) {

    switch result.rawValue {
    case MFMailComposeResult.Cancelled.rawValue:
        print("Mail cancelled")
    case MFMailComposeResult.Saved.rawValue:
        print("Mail saved")
    case MFMailComposeResult.Sent.rawValue:
        print("Mail sent")
    case MFMailComposeResult.Failed.rawValue:
        print("Mail sent failure: %@", [error!.localizedDescription])
    default:
        break
    }
    // Dismiss the mail compose view controller.
    controller.dismissViewControllerAnimated(true, completion: nil)
}

回答4:

In swift 3, you can use this clear code:

 @IBAction func sendMail(_ sender: Any) {

        print(MFMailComposeViewController.canSendMail())
        if MFMailComposeViewController.canSendMail() {
            let mail = MFMailComposeViewController()
            mail.mailComposeDelegate = self
            mail.setToRecipients(["test@test.com"])
            mail.setMessageBody("<p>This is test Mail!</p>", isHTML: true)

            present(mail, animated: true)
        } else {
             let email = "test@test.com"
             if let url = URL(string: "mailto:\(email)") {
             UIApplication.shared.open(url)
             }

        }


    }

    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        controller.dismiss(animated: true)
        switch result {
        case .cancelled:
            print("Mail cancelled")
        case .saved:
            print("Mail saved")
        case .sent:
            self.allertInfo(_title: "Mail Info", _message: "Mail is sent successfuly", _actionTitle: "OK")
            print("Mail sent")
        case .failed:
            self.allertInfo(_title: "Mail Info", _message: "Mail isn't sent.",
_actionTitle: "OK")
            print("Mail sent failure: \(error?.localizedDescription)")
        default:
            break
        }

    }

    func allertInfo(_title:String, _message:String, _actionTitle:String) {

        let alert = UIAlertController(title: _title, message: _message, preferredStyle: UIAlertControllerStyle.alert)
        alert.addAction(UIAlertAction(title: _actionTitle, style: UIAlertActionStyle.default, handler: nil))
        self.present(alert, animated: true, completion: nil)

    }

回答5:

In addition to using .value, don't forget to add to break to each case statement, see Apple's official version: https://developer.apple.com/library/iOS/samplecode/MessageComposer/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010161

来源：https://stackoverflow.com/questions/24311073/mfmailcomposeviewcontroller-in-swift