App crashes after send button in Mail Composer is pressed

Question

I have a mailHelper class like following:

class MailHelper: NSObject, MFMailComposeViewControllerDelegate {
    //MARK: Mail Function
    func configuredInquiryMailComposeViewController(rootViewController: UIViewController) {
        let mailComposerVC = MFMailComposeViewController()
        mailComposerVC.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.whiteColor(), NSFontAttributeName: UIFont(name: "AvenirNext-Medium", size: 20)!]
        mailComposerVC.navigationBar.tintColor = UIColor.whiteColor()
        mailComposerVC.navigationBar.translucent = false
        mailComposerVC.mailComposeDelegate = self
        mailComposerVC.setToRecipients(["(email)"])
        mailComposerVC.setSubject("(title)")
        mailComposerVC.setMessageBody("[Please write your inquiries below. We will reply shortly]", isHTML: false)

        if MFMailComposeViewController.canSendMail() {
            rootViewController.presentViewController(mailComposerVC, animated: true, completion: nil)
        } else {
                            showSendMailErrorAlert()
        }
    }

    func showSendMailErrorAlert() {
        let sendMailErrorAlert = UIAlertController(title: "Could Not Send Email", message: "Your device could not send e-mail.  Please check e-mail configuration and try again.", preferredStyle: UIAlertControllerStyle.Alert)
        let cancelAction: UIAlertAction = UIAlertAction(title: "Ok", style: .Cancel, handler: nil)
        sendMailErrorAlert.addAction(cancelAction)
        self.presentViewController(sendMailErrorAlert, animated: true, completion: nil)
    }

    // MARK: MFMailComposeViewControllerDelegate Method
    func mailComposeController(controller: MFMailComposeViewController, didFinishWithResult result: MFMailComposeResult, error: NSError?) {
        controller.dismissViewControllerAnimated(true, completion: nil)
    }

}

Then I call this helper function in my main view controller:

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    if (indexPath.section == 0 && indexPath.row == 0) {
                let mailHelperClass = MailHelper()
               mailHelperClass.configuredInquiryMailComposeViewController(self)
            }
}

When I click the cell in tableview in main view controller, Mail Composer is successfully shown. The problem is that whenever I click "Send" or "Cancel" button in the mail composer, it crashes the app.

To make sure whether this helper class is wrong, I got rid of the helper class and migrated all mail composer related functions into my main view controller. Then, it worked whenever I clicked "Send" or "Cancel" button. What am I doing wrong in my mail helper class?

When it crashes, it does not give me any error message.

@Anbu.Karthik just edited my question. It throws no error message even if i set exceptional breakpoint — Kahsn, Mar 17 '16 at 07:10
see this link http://stackoverflow.com/questions/5386160/how-to-enable-nszombie-in-xcode, it will capture your exception — Anbu.Karthik, Mar 17 '16 at 07:13
@Anbu.Karthik, It says `[(app_name).MailHelper respondsToSelector:]: message sent to deallocated instance 0x1294bb9e0`. Any ideas?? Don't think this msg is too helpful. — Kahsn, Mar 17 '16 at 07:16
@FahriAzimov, I would really appreciate if you can give more idea about retaining the object! — Kahsn, Mar 17 '16 at 07:23

score 4 · Accepted Answer · answered Mar 17 '16 at 07:18

4

Your problem here is not obvious, but it's the problem of the MFMailComposeViewControllerDelegate. When you present mail composer using your custom class, you have assigned object of that class as a delegate, and didn't retain the object. As soon as object of MailHelper left it's scope, it got released, and when you have tried to send or cancel on mail composer, it sent message to the deallocated object, since object was not there anymore your app crashed, that's it!

Also, you should be checking if mail composer canSendMail() before creating the object of the mail composer, if it can't send mail, why do you create the object?

Hope this helps!

answered Mar 17 '16 at 07:18

Fahri Azimov

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Can you explain a bit more about "left it's scope"? And how can I retain the object in my case? – Kahsn Mar 17 '16 at 07:20
All the objects created have their scopes, during which they live. For example, if you declared the object as a instance variable, and created it elsewhere in the class, it's scope is the class's lifetime, which means that object i will live while your class is alive (if you don't release it manually before, of course). In your case, `MailHelper`'s object was declared and created inside the method, thus had a scope of the method, which means, when method is finished, all the objects created inside the method are purged. – Fahri Azimov Mar 17 '16 at 07:23
According your second question, there are many possible ways of retaining the object, you can create `property` with `strong` reference (`retain` for non ARC environment), you can declare it as a instance variable, etc. – Fahri Azimov Mar 17 '16 at 07:27
Very helpful! Thank you! Solved the problem – Kahsn Mar 17 '16 at 07:37

App crashes after send button in Mail Composer is pressed

1 Answers1