a.swift

let handler = VNImageRequestHandler(
  cgImage: cgImage,
  orientation: inferOrientation(image: image),
  options: [VNImageOption: Any]()
)

let request = VNDetectTextRectanglesRequest(completionHandler: { [weak self] request, error in
  DispatchQueue.main.async {
    self?.handle(image: image, request: request, error: error)
  }
})

request.reportCharacterBoxes = true

do {
  try handler.perform([request])
} catch {
  print(error as Any)
}