Generate QRCode Image for a given string.

QRString

import UIKit

extension String {
    
    func qrCode() -> UIImage? {
        let data = self.data(using: .isoLatin1)
        guard let qrFilter = CIFilter(name: "CIQRCodeGenerator") else {
            return nil
        }
        qrFilter.setValue("M", forKey: "inputCorrectionLevel")
        qrFilter.setValue(data, forKey: "inputMessage")
        let scale: CGFloat = 100
        
        // Render the image into a CoreGraphics image
        guard let output = qrFilter.outputImage else {
            return nil
        }
        let ciContext = CIContext()
        guard let cgImage = ciContext.createCGImage(output, from: output.extent) else {
            return nil
        }
        
        //Scale the image usign CoreGraphics
        UIGraphicsBeginImageContext(CGSize(width: output.extent.size.width * scale, height: output.extent.size.width * scale))
        
        guard let graphicsContext = UIGraphicsGetCurrentContext() else {
            return nil
        }
        graphicsContext.interpolationQuality = CGInterpolationQuality.none
        graphicsContext.draw(cgImage, in: graphicsContext.boundingBoxOfClipPath)
        guard let previewImage = UIGraphicsGetImageFromCurrentImageContext() else {
            return nil
        }
        //Cleaning up .
        UIGraphicsEndImageContext()
        // Rotate the image
        guard let qrCgImage = previewImage.cgImage else {
            return nil
        }
        return UIImage(cgImage: qrCgImage, scale: previewImage.scale, orientation: .downMirrored)
    }
}