如何在xamarin ios应用中打开邮件应用窗口？

using MessageUI;

// ...

MFMailComposeViewController mailController;
mailController = new MFMailComposeViewController();
mailController.SetMailComposeDelegate(new MailComposeDelegate());

mailController.SetSubject("邮件主题");
mailController.SetToRecipients(new string[] { "收件人邮箱地址" });
mailController.SetCcRecipients(new string[] { "抄送人邮箱地址" });
mailController.SetBccRecipients(new string[] { "密送人邮箱地址" });
mailController.SetMessageBody("邮件正文", false);

public class MailComposeDelegate : MFMailComposeViewControllerDelegate
{
    public override void Finished(MFMailComposeViewController controller, MFMailComposeResult result, NSError error)
    {
        // 处理邮件发送结果
        switch (result)
        {
            case MFMailComposeResult.Sent:
                Console.WriteLine("邮件已发送");
                break;
            case MFMailComposeResult.Cancelled:
                Console.WriteLine("邮件发送已取消");
                break;
            case MFMailComposeResult.Saved:
                Console.WriteLine("邮件已保存");
                break;
            case MFMailComposeResult.Failed:
                Console.WriteLine("邮件发送失败");
                break;
        }

        // 关闭邮件应用窗口
        controller.DismissViewController(true, null);
    }
}

// 在当前视图控制器中显示邮件应用窗口
PresentViewController(mailController, true, null);