How to create a barcode

Paul Hudson    September 20th 2017    @twostraws

You can generate a string into a traditional barcode using iOS using Core Image, but you should make sure and convert your input string to a Data using String.Encoding.ascii to ensure compatibility. Here's a function you can use that wraps it all up neatly, including scaling up the barcode so it's a bit bigger:

func generateBarcode(from string: String) -> UIImage? {
    let data = string.data(using: String.Encoding.ascii)

    if let filter = CIFilter(name: "CICode128BarcodeGenerator") {
        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
}

With that method in place, you can now write code like this:

let image = generateBarcode(from: "Hacking with Swift")

Available from iOS 8.0

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