当我添加 AVCaptureMovieFileOutput 时，我的 captureOutput 委托中的代码停止运行？

Question

我正在制作一个视频录制应用程序，但我遇到的问题是当代码canAddOutput(movieFileOutput)被调用时，我的captureOutput delegate中的代码停止运行。 只有当我在stopRecording()函数中调用removeOutput(movieFileOutput)时，代码才会再次开始运行。 为什么会这样？

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

print("gets called every video frame")
    

    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
        return
    }
    
}


@IBAction func didPressRecordVideo(_ sender: Any) {

    recordVideoButton.isSelected.toggle()

    recordVideoButton.setImage(UIImage(named: recordVideoButton.isSelected ? "stoprecordbutton" : "recordButton"), for: .normal)


    if movieFileOutput.isRecording == false {
    if recordVideoButton.isSelected {
            print("start recording")
        

        // Setup Microphone
        let microphone = AVCaptureDevice.default(for: AVMediaType.audio)!
        do {
            let micInput = try AVCaptureDeviceInput(device: microphone)
            if captureSession.canAddInput(micInput) {
                captureSession.addInput(micInput)
                micInput2 = micInput
            }
            
            //hide top camera button when video is recording
            switchToCameraButton.isHidden = true
            
        } catch {
            print("Error setting device audio input: \(error)")
        }
        


            if captureSession.canAddOutput(movieFileOutput) {
            captureSession.addOutput(movieFileOutput)
                
            }

        
            outputURL = tempURL()
            movieFileOutput.startRecording(to: outputURL, recordingDelegate: self)
        


        }
    }
        
  else {
        stopRecording()
    }
 }