QR Code Generator written in Swift 4

generateQRcode.swift

import Quartz

extension CGImage {
    class func qrCodeImage(from string: String, scale: CGFloat = 1) -> CGImage? {
        let stringData = string.data(using: .utf8)
        let transform = CGAffineTransform(scaleX: scale, y: scale)

        guard let filter = CIFilter(name: "CIQRCodeGenerator") else {
            return nil
        }
        filter.setValue(stringData, forKey: "inputMessage")
        filter.setValue("H", forKey: "inputCorrectionLevel")
        
        guard let ciImage = filter.outputImage?.transformed(by: transform) else {
            return nil
        }
        
        let cgImage = CIContext().createCGImage(ciImage, from: ciImage.extent)
        return cgImage
    }
    
    func data(type: CFString, dpi: CGFloat = 72) -> NSData? {
        let prop: [CFString : Any] = [kCGImagePropertyIPTCImageType: 1.0,
                                      kCGImagePropertyDPIWidth: dpi,
                                      kCGImagePropertyDPIHeight: dpi]
        let outputData = NSMutableData()
        let destination = CGImageDestinationCreateWithData(outputData, type, 1, nil)!
        CGImageDestinationAddImage(destination, self, prop as CFDictionary)
        CGImageDestinationFinalize(destination)
        return outputData
    }
}

// QRコード連続並列生成
let scale: CGFloat = 5
let dpi: CGFloat = 144
let maxCount = 100

// 並列処理で一括生成
DispatchQueue.concurrentPerform(iterations: maxCount) { num in
    autoreleasepool {
        let numberString = String(format: "%04d", num)
        if let pngData = CGImage.qrCodeImage(from: numberString, scale: scale)?.data(type: kUTTypePNG, dpi: dpi) {
            pngData.write(toFile: "/tmp/\(numberString).png", atomically: true)
        }
    }
}