qr code from string

String+QR.swift

import Foundation

extension String {
    func qrCode() -> UIImage? {
        if self.isEmpty { return nil }

        let data = self.data(using: String.Encoding.ascii)

        if let filter = CIFilter(name: "CIQRCodeGenerator") {
            filter.setValue(data, forKey: "inputMessage")
            let transform = CGAffineTransform(scaleX: 3, y: 3)

            if let output = filter.outputImage?.transformed(by: transform) {
                return UIImage(ciImage: output)
            }
        }

        return nil
    }
}