Swift 2:第二次尝试表视图后，电子邮件取消按钮停止工作

Question

我使用的是一个表格视图，其中有一个单元格，上面写着"向我们发送反馈"。它打开了带有要发送的预设信息的电子邮件应用程序。我可以发送电子邮件和/或取消它，但当我第一次取消它时，停留在表格视图上，再次点击单元格打开电子邮件，我不能再次取消它。它只是停留在电子邮件视图中。

建议？

我的代码如下：

import UIKit
import MessageUI
class FeedbackViewController: UITableViewController, MFMailComposeViewControllerDelegate {
    let mailComposerVC = MFMailComposeViewController()
    override func viewDidLoad() {
        super.viewDidLoad()
        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false
        // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
        // self.navigationItem.rightBarButtonItem = self.editButtonItem()
    }
    override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        if indexPath.section == 0 && indexPath.row == 0
        {
            let alertController = UIAlertController(title: "Rate Us", message: "nAre you enjoying our app? Please rate us in the app store!nnElse if you know of ways we can make our app better, please send us feedback so we can improve the experience for you!nnThank you!nnTimmy Caish", preferredStyle: .Alert)
            alertController.addAction(UIAlertAction(title: "Rate on iTunes", style: .Default, handler: {
                (action: UIAlertAction!) -> Void in
                UIApplication.sharedApplication().openURL((NSURL(string: "http://google.com")!))
                print("Rate us alert button worked.")
                print("Send to iTunes")
            }))
            alertController.addAction(UIAlertAction(title: "Send Us Feedback", style: .Default, handler: {
                (action: UIAlertAction!) in
                print("Rate Us feeback button worked.")
                let mailComposeViewController = self.configureMailComposeViewController()
                if MFMailComposeViewController.canSendMail()
                {
                    self.presentViewController(mailComposeViewController, animated: true, completion: nil)
                }
                else
                {
                    self.showSendMailErrorAlert()
                }
            }))
            alertController.addAction(UIAlertAction(title: "Cancel", style: .Default, handler: { (action: UIAlertAction) in
                print("Rate us cancel button worked.")
            print("Rate us")
            }))
            presentViewController(alertController, animated: true, completion: nil)
        }

        if indexPath.section == 0 && indexPath.row == 1
        {
            let mailComposeViewController = configureMailComposeViewController()
            if MFMailComposeViewController.canSendMail()
            {
                self.presentViewController(mailComposeViewController, animated: true, completion: nil)
            }
            else
            {
                self.showSendMailErrorAlert()
            }
            print("Send us feedback")
        }
    }
    func configureMailComposeViewController() -> MFMailComposeViewController {
        mailComposerVC.mailComposeDelegate = self
        mailComposerVC.setToRecipients(["[e-mail]"])
        mailComposerVC.setSubject("Weather Simplicity Feedback")
        mailComposerVC.setMessageBody("Hello,nnI would like to share the following feedback...nn", isHTML: false)
        return mailComposerVC
    }
    func showSendMailErrorAlert() {
        let sendMailErrorAlert = UIAlertController(title: "Error", message: "Your device could not send the email. Check your email configurations and try again.", preferredStyle: UIAlertControllerStyle.Alert)
        let okay = UIAlertAction(title: "Okay", style: UIAlertActionStyle.Default, handler: nil)
        sendMailErrorAlert.addAction(okay)
        self.presentViewController(sendMailErrorAlert, animated: true, completion: nil)
    }
    func mailComposeController(controller: MFMailComposeViewController, didFinishWithResult result: MFMailComposeResult, error: NSError?) {
        switch result {
        case MFMailComposeResultCancelled:
            print("Cancelled mail")
            break
        case MFMailComposeResultSent:
            print("Message sent")
            break
        default:
            break
        }
        self.dismissViewControllerAnimated(true, completion: nil)
    }
}

Answer 1

只有在didSelectRow中需要时才尝试创建新的mailViewController，而不是在创建视图控制器时。这将确保它每次都是干净的，除非需要，否则不会创建，并可能解决第二次取消不起作用的问题。