Create QR code

QRCode.swift

import CoreImage

struct QRCode {

    static func generateQRCode(from url: String, 
                               width: Double = 512.0,
                               heigth: Double = 512.0,
                               foregroundColor: CIColor = .black,
                               backgroundColor: CIColor = .white) -> CGImage? {
        let data = url.data(using: String.Encoding.ascii)

        if let filter = CIFilter(name: "CIQRCodeGenerator") {
            filter.setValue(data, forKey: "inputMessage")

            guard let outputImage = filter.outputImage else { return nil }
            let scaleX = width / outputImage.extent.size.width
            let scaleY = heigth / outputImage.extent.size.height
            let transformedImage = outputImage.transformed(by: CGAffineTransform(scaleX: scaleX, y: scaleY))

            if let colorInvertFilter = CIFilter(name: "CIColorInvert") {
                colorInvertFilter.setValue(transformedImage, forKey: kCIInputImageKey)

                let parameters = [
                    kCIInputImageKey: colorInvertFilter.outputImage!,
                    "inputColor0": foregroundColor,
                    "inputColor1": backgroundColor
                ]
                if let colorFilter = CIFilter(name: "CIFalseColor", parameters: parameters) {
                    let context = CIContext()
                    if let cgImg = context.createCGImage(colorFilter.outputImage!, from: colorFilter.outputImage!.extent) {
                        return cgImg
                    }
                }
            }
        }

        return nil
    }

}