应用程序按钮打开电子邮件,但不会关闭窗口并返回应用程序

看起来你忘记实现了MFMailComposeViewControllerDelegate,添加这个:

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