How to get greyscale video image from camera?

I am developing a camera app and need to get realtime greyscale video from camera. I am using AVFoundation framework and set video output like this;

private func setupCamera() {
	...
	let videoOutput = AVCaptureVideoDataOutput()
	videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : Int(kCVPixelFormatType_32BGRA)]
	videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue.main)
	...
}

For captureOutput, I write like this;

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
		let imageBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
        
        let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)!
        let bytesPerRow = UInt(CVPixelBufferGetBytesPerRow(imageBuffer))
        let width = CVPixelBufferGetWidth(imageBuffer)
        let height = CVPixelBufferGetHeight(imageBuffer)
        let bitsPerCompornent = 8
        var colorSpace = CGColorSpaceCreateDeviceGray()
        var bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
        
        let context = CGContext(data: baseAddress, width: Int(width), height: Int(height), bitsPerComponent: Int(bitsPerCompornent), bytesPerRow: Int(bytesPerRow), space: colorSpace, bitmapInfo: bitmapInfo.rawValue)! as CGContext
        let imageRef = context.makeImage()!
        let image = UIImage(cgImage: imageRef, scale: 1.0, orientation: UIImage.Orientation.up)
        
        CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
        captureImageView.image = image
}

The point is

var colorSpace = CGColorSpaceCreateDeviceGray()
var bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)

The image I can get is something like 'greyscale video' but not complete video image.

How can I get complete greyscale video?

Please advise me if anyone knows the answer to get greyscale realtime video.