如何遍历MFMessageViewController的视图层次结构？

问：

我想遍历MFMessageComposerController的视图层次结构，以便可以获取填充消息的UITextField实例。这是我在 Swift 中为呈现 MFMessageController 所做的代码。如何遍历其层次结构？

代码：

@IBAction func sendSmsClick(_ sender: AnyObject) {
        guard MFMessageComposeViewController.canSendText() else {
        return
    }

    let messageVC = MFMessageComposeViewController()
    messageVC.view.endEditing(true)
    messageVC.body = "Enter a message";
    messageVC.recipients = ["Enter tel-nr"]
    messageVC.messageComposeDelegate = self;
    NSLog("Subviews %@", messageVC.view.subviews);
   // self.view.endEditing(true)

self.present(messageVC, animated: false) {
   
}
}

func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
    switch (result.rawValue) {
        case MessageComposeResult.cancelled.rawValue:
        print("Message was cancelled")
        self.dismiss(animated: true, completion: nil)
    case MessageComposeResult.failed.rawValue:
        print("Message failed")
        self.dismiss(animated: true, completion: nil)
    case MessageComposeResult.sent.rawValue:
        print("Message was sent")
        self.dismiss(animated: true, completion: nil)
    default:
        break;
    }
}

谁能告诉如何遍历MFMessageViewController的视图层次结构？

NSLOG 的结果

我的议程是模仿这个应用程序中显示的内容。查找文本字段并禁用编辑 .来自Appstore的应用程序：