Is there a way to generate QR code image on iOS

Question

Is there a standard way to generate a QR code and attach it to a mail item from iOS client app (no server code)?

Answer 1

Using Swift 2

import UIKit
import CoreImage

func createQRFromString(str: String) -> CIImage? {
    let stringData = str.dataUsingEncoding(NSUTF8StringEncoding)

    let filter = CIFilter(name: "CIQRCodeGenerator")

    filter?.setValue(stringData, forKey: "inputMessage")

    filter?.setValue("H", forKey: "inputCorrectionLevel")

    return filter?.outputImage
}

if let img = createQRFromString("Hello world program created by someone") {
    let somImage = UIImage(CIImage: img, scale: 1.0, orientation: UIImageOrientation.Down)
}

Swift 3.0

import UIKit
import CoreImage

func createQRFromString(_ str: String) -> CIImage? {
        let stringData = str.data(using: String.Encoding.utf8)

        let filter = CIFilter(name: "CIQRCodeGenerator")

        filter?.setValue(stringData, forKey: "inputMessage")

        filter?.setValue("H", forKey: "inputCorrectionLevel")

        if let img = createQRFromString("Hello world program created by someone") {
            let somImage = UIImage(ciImage: img, scale: 1.0, orientation: UIImageOrientation.down)
        }

        return filter?.outputImage
    }

if let img = createQRFromString("Hello world program created by someone") {
            let somImage = UIImage(ciImage: img, scale: 1.0, orientation: UIImageOrientation.down)
        }

Swift 4.2

private func createQRFromString(str: String) -> CIImage? {
        let stringData = str.data(using: .utf8)

        let filter = CIFilter(name: "CIQRCodeGenerator")
        filter?.setValue(stringData, forKey: "inputMessage")
        filter?.setValue("H", forKey: "inputCorrectionLevel")

        return filter?.outputImage
    }

    var qrCode: UIImage? {
        if let img = createQRFromString(str: "Hello world program created by someone") {
            let someImage = UIImage(
                ciImage: img,
                scale: 1.0,
                orientation: UIImage.Orientation.down
            )
            return someImage
        }

        return nil
    }