import AVFoundation

// 创建 AVCaptureSession
let captureSession = AVCaptureSession()

// 设置 AVCaptureVideoDataOutput
let videoOutput = AVCaptureVideoDataOutput()
videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA)]

// 将视频输出添加到 AVCaptureSession
videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "sample buffer delegate"))
captureSession.addOutput(videoOutput)

// 设置 AVCaptureVideoPreviewLayer
let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.bounds
view.layer.addSublayer(previewLayer)

// 开始 AVCaptureSession
captureSession.startRunning()