如何在MFMessageComposeViewController中启用摄像头？

<key>NSCameraUsageDescription</key>
<string>需要访问您的摄像头以拍摄照片或视频</string>

import MessageUI

class ViewController: UIViewController, MFMessageComposeViewControllerDelegate {
    // ...
    
    func sendMessage() {
        if MFMessageComposeViewController.canSendText() {
            let messageVC = MFMessageComposeViewController()
            messageVC.messageComposeDelegate = self
            messageVC.body = "这是一条短信"
            
            // 启用摄像头
            messageVC.showsCameraControls = true
            messageVC.cameraCaptureMode = .photo
            
            present(messageVC, animated: true, completion: nil)
        }
    }
    
    // 实现MFMessageComposeViewControllerDelegate方法
    func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
        dismiss(animated: true, completion: nil)
    }
    
    // ...
}