Ios 正在尝试从swift中的应用发送电子邮件

我试图在myViewController上显示一个电子邮件弹出窗口，但我收到了错误消息

使用未解析的标识符“present”

在线

现在（作曲家，动画：真）

值得注意的是，按钮位于collectionView单元格中。如何修复此错误，以便在按下按钮时屏幕上显示电子邮件概览

这是我的密码

import MessageUI

class MessagesViewCell: UICollectionViewCell, MFMailComposeViewControllerDelegate {

@IBOutlet weak var textLabel: UILabel!
@IBOutlet weak var imageView: UIImageView!
@IBAction func emailButtonTapped(_ sender: Any) {
    showMailComposer()
}

func showMailComposer() {
    guard MFMailComposeViewController.canSendMail() else {
        return
    }

    let composer = MFMailComposeViewController()
    composer.mailComposeDelegate = self
    composer.setToRecipients(["email"])
    composer.setSubject("")
    composer.setMessageBody("", isHTML: false)
    composer.present(composer, animated: true)
    present(composer, animated: true)
}
}

extension MessagesViewController: MFMailComposeViewControllerDelegate {

func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
    if let _ = error {
        controller.dismiss(animated: true)
    }
    switch result {
    case .cancelled:
        print("Cancelled")
    case .failed:
        print("Failed to send")
    case .saved:
        print("Saved")
    case .sent:
        print("Email Sent")
    default:
        break
    }
    controller.dismiss(animated: true)
}
}

---

解决此问题的最简单方法是将

UIViewController

的弱引用传递给

UICollectionViewCell

。然后在弱引用传递的

UIViewController

上调用present，而不是在

UICollectionViewCell

的实例上调用它。以下是方法：

在

cellForItem

方法中：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Identifier, for: indexPath) as! MessagesViewCell
    cell.controller = self
    //...
    return cell
}

在

消息iewcell

中：

class MessagesViewCell: UICollectionViewCell, MFMailComposeViewControllerDelegate {
    weak var controller: UIViewController?
func showMailComposer() {
    guard MFMailComposeViewController.canSendMail() else {
        return
    }

    let composer = MFMailComposeViewController()
    composer.mailComposeDelegate = self
    composer.setToRecipients(["email"])
    composer.setSubject("")
    composer.setMessageBody("", isHTML: false)
    composer.present(composer, animated: true)
    controller?.present(composer, animated: true)
}

---

您需要从

UIViewController

的实例调用

present

。单元格不能显示新的视图控制器。您可以使用委派将按钮点击事件传递回视图控制器。这是否回答了您的问题？