iOS：自定义activityViewController

Question

嗨，我实现了activityViewController，我的activityItems是文本，当我按下按钮时会弹出，我选择邮件IMPORTENT：当我选择它时，我在（activityItems）中的文本转到邮件正文但我想让它进入发件人消息文本字段（To :)

我应该如何实现这个???

@IBAction func activityView(_ sender: UIButton) {
    let text = "Mahdi.m@email.com"
    let img = UIImage(named: "Buliding")!
    let activityViewController = UIActivityViewController(activityItems: [text, img], applicationActivities: nil)
    activityViewController.popoverPresentationController?.sourceView = self.view
    activityViewController.excludedActivityTypes = [ UIActivityType.airDrop]
    self.present(activityViewController, animated: true, completion: nil)
}