create_qr.swift

 private func createCIImage() -> CIImage? {
        guard let filter = CIFilter(name: "CIQRCodeGenerator") else {
            return nil
        }
        filter.setDefaults()
        filter.setValue(url.data(using: String.Encoding.ascii), forKey: "inputMessage")
        filter.setValue("H", forKey: "inputCorrectionLevel")
        //https://www.qrcode.com/en/about/error_correction.html
        return filter.outputImage
 }