AVFoundation - beginSession

av_foundation_begin_session.swift

func beginSession() {
  do {
    let deviceInput = try AVCaptureDeviceInput(device: self.captureDevice)
    self.captureSession.addInput(deviceInput)
  } catch {
    //  Handle error and return early.
  }

  self.previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
  if let preview = self.previewLayer {
    self.view.layer.addSublayer(preview)
    preview.frame = self.view.layer.frame
    self.captureSession.startRunning()
  }
}