How can I generate a barcode from a string in Swift?

Question

I am a new iOS developer. I was wondering how can I generate a barcode in Swift.

I have the code already, there are multiple resources from where to learn how to read a barcode, but I didn't find any that talks about generating one from a string.

Thanks a lot!

P.S. I know there is a similar question about this, but it's for Objective-C. I don't know Obj-C and I find it difficult coming from .NET.

Matteo Pacini · Accepted Answer · 2019-06-08T14:08:57.747

85

You could use a CoreImage (import CoreImage) filter to do that!

    class Barcode {
        class func fromString(string : String) -> UIImage? {
             let data = string.data(using: .ascii)
             if let filter = CIFilter(name: "CICode128BarcodeGenerator") {
                  filter.setValue(data, forKey: "inputMessage")
                  if let outputCIImage = filter.outputImage {
                       return UIImage(ciImage: outputCIImage)
                  }
             }
             return nil
        }
    }

    let img = Barcode.fromString("whateva")

A newer version, with guard and failable initialiser:

extension UIImage {

    convenience init?(barcode: String) {
        let data = barcode.data(using: .ascii)
        guard let filter = CIFilter(name: "CICode128BarcodeGenerator") else {
            return nil
        }
        filter.setValue(data, forKey: "inputMessage")
        guard let ciImage = filter.outputImage else {
            return nil
        }
        self.init(ciImage: ciImage)
    }

}

Usage:

let barcode = UIImage(barcode: "some text") // yields UIImage?

According to the docs :

Generates an output image representing the input data according to the ISO/IEC 15417:2007 standard. The width of each module (vertical line) of the barcode in the output image is one pixel. The height of the barcode is 32 pixels. To create a barcode from a string or URL, convert it to an NSData object using the NSASCIIStringEncoding string encoding.

edited Jun 08 '19 at 14:08

answered Feb 16 '15 at 13:24

Matteo Pacini

17,507
3
58
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2

Amazing !! But then, I wonder why people create more or less complex libraries to handle barcode generation. Where are differences between this and libs ? – PAD Oct 02 '15 at 16:42
1

@PAD Well, these Core Image filters are quite new (iOS >= 8.0). Before iOS 8, generating barcodes would have been done through these libraries I guess. – Matteo Pacini Oct 03 '15 at 09:21
It should be noted there are three different types of Code128. This implementation uses subtype C. If you are looking to generate Code 128 type A or B, you may need to look into the ZXing library. – AtomicBoolean Jun 29 '16 at 17:58
Amazing !! Thanks, If I want to create other barcodes like UPCA, UPCE with HRI values is it possible with this? – Dhaval Jun 07 '17 at 06:27
what is the CIFilter name for Barcode Code28, Code39 and CODABAR? – JkAlombro Sep 19 '18 at 02:27
This doesn't generate a barcode with the source string below like [this](https://www.computalabel.com/Images/C128.png). – Gerardo Cauich Apr 17 '20 at 10:28
Starting with iOS 13 (not 100% sure though) you can `import CoreImage.CIFilterBuiltins` and use something like `let filter = CIFilter.code128BarcodeGenerator()` which provides properties for the relevant keys. The key `inputMessage` becomes `filter.message = …` – D. Mika Apr 26 '21 at 15:00

score 17 · Answer 2 · answered Mar 15 '17 at 00:44

Improved code:

Barcode scaling
Set barcode image margin
Convert the UIImage to NSData (for some reason it wasn't possible with the code above).
It won't fail when sharing the barcode image (probably because of the same bug)

Swift 3

func generateBarcode(from string: String) -> UIImage? {

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

    if let filter = CIFilter(name: "CICode128BarcodeGenerator") {
        filter.setDefaults()
        //Margin
        filter.setValue(7.00, forKey: "inputQuietSpace")
        filter.setValue(data, forKey: "inputMessage")
        //Scaling
        let transform = CGAffineTransform(scaleX: 3, y: 3)

        if let output = filter.outputImage?.applying(transform) {
            let context:CIContext = CIContext.init(options: nil)
            let cgImage:CGImage = context.createCGImage(output, from: output.extent)!
            let rawImage:UIImage = UIImage.init(cgImage: cgImage)

            //Refinement code to allow conversion to NSData or share UIImage. Code here:
            //http://stackoverflow.com/questions/2240395/uiimage-created-from-cgimageref-fails-with-uiimagepngrepresentation
            let cgimage: CGImage = (rawImage.cgImage)!
            let cropZone = CGRect(x: 0, y: 0, width: Int(rawImage.size.width), height: Int(rawImage.size.height))
            let cWidth: size_t  = size_t(cropZone.size.width)
            let cHeight: size_t  = size_t(cropZone.size.height)
            let bitsPerComponent: size_t = cgimage.bitsPerComponent
            //THE OPERATIONS ORDER COULD BE FLIPPED, ALTHOUGH, IT DOESN'T AFFECT THE RESULT
            let bytesPerRow = (cgimage.bytesPerRow) / (cgimage.width  * cWidth)

            let context2: CGContext = CGContext(data: nil, width: cWidth, height: cHeight, bitsPerComponent: bitsPerComponent, bytesPerRow: bytesPerRow, space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: cgimage.bitmapInfo.rawValue)!

            context2.draw(cgimage, in: cropZone)

            let result: CGImage  = context2.makeImage()!
            let finalImage = UIImage(cgImage: result)

            return finalImage

        }
    }

    return nil
}

@Rushi, how are you trying to read the barcode? With a scanner or through the app? — castillejoale, Aug 31 '17 at 20:32
worked perfact. but my image size is too small at that time so not readable. — Rushi trivedi, Sep 01 '17 at 12:48
Working solution, but code is unsafe with a lot of force unwrapping. Why at first you create a cgImage, then create a rawImage: UIImage from it and then getting back the cgimage from the UIImage? There is some difference? — Andreas777, Mar 23 '18 at 09:36

score 10 · Answer 3 · edited Oct 22 '20 at 07:08

10

If your deployment target is at least iOS 8, you can use Core Image. Here is my BarcodeGenerator class (you need to import CoreImage):

class BarcodeGenerator {
    enum Descriptor: String {
        case code128 = "CICode128BarcodeGenerator"
        case pdf417 = "CIPDF417BarcodeGenerator"
        case aztec = "CIAztecCodeGenerator"
        case qr = "CIQRCodeGenerator"
    }

    class func generate(from string: String, 
                         descriptor: Descriptor, 
                               size: CGSize) -> CIImage? {
        let filterName = descriptor.rawValue

        guard let data = string.data(using: .ascii),
            let filter = CIFilter(name: filterName) else {
                return nil
        }

        filter.setValue(data, forKey: "inputMessage")

        guard let image = filter.outputImage else {
            return nil
        }

        let imageSize = image.extent.size

        let transform = CGAffineTransform(scaleX: size.width / imageSize.width,
                                               y: size.height / imageSize.height)
        let scaledImage = image.transformed(by: transform)

        return scaledImage
    }
}

It can be used like this

BarcodeGenerator.generate(from: "barcode-string", 
                     descriptor: .code128, 
                          size: CGSize(width: 800, height: 300))

edited Oct 22 '20 at 07:08

MilanPanchal

2,865
1
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answered Jan 16 '18 at 13:13

Luca Torella

7,094
4
35
47

1

what is the CIFilter name for Barcode Code28, Code39 and CODABAR? – JkAlombro Sep 19 '18 at 01:32
only those 4 descriptors are supported as you can see here https://developer.apple.com/documentation/coreimage/cibarcodedescriptor – Luca Torella Sep 19 '18 at 07:58
Unless I'm missing something they seem to have replaced code128 with dataMatrix as of Jan 19 – ChrisH Jan 17 '19 at 17:59
if you go to the link i posted above, I still see code128 and I don't see DataMatrix. – Luca Torella Jan 18 '19 at 13:47
this is code128 https://developer.apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/CICode128BarcodeGenerator – Luca Torella Jan 18 '19 at 13:47
@LucaTorella When I detect barcode or qrCode with AVCaptureSession, you know how I get the descriptor? In order to use your class and recreate barcode on my app – Szanownego Jun 03 '19 at 08:52
each AVMetadataObject has a ObjectType property. You need to map this enum to the Descriptor. Check https://developer.apple.com/documentation/avfoundation/avmetadataobject/objecttype – Luca Torella Jun 04 '19 at 09:19

score 0 · Answer 4 · answered May 28 '20 at 08:47

Use like this,

func createBarcodeFromString(barcode:String)->UIImage?{

    let data = self.data(using: .isoLatin1)
    guard let filter = CIFilter(name: "CICode128BarcodeGenerator") else {
        return nil
    }
    filter.setValue(data, forKey: "inputMessage")
    filter.setValue(7.0, forKey:"inputQuietSpace")
    guard var ciImage = filter.outputImage else {
        return nil
    }

    let imageSize = ciImage.extent.integral
    let outputSize = CGSize(width:320, height: 60)
    ciImage = ciImage.transformed(by:CGAffineTransform(scaleX: outputSize.width/imageSize.width, y: outputSize.height/imageSize.height))

    let image = convertCIImageToUIImage(ciimage: ciImage)
    return image
}

func convertCIImageToUIImage(ciimage:CIImage)->UIImage{
    let context:CIContext = CIContext.init(options: nil)
    let cgImage:CGImage = context.createCGImage(ciimage, from: ciimage.extent)!
    let image:UIImage = UIImage.init(cgImage: cgImage)
    return image
}

How can I generate a barcode from a string in Swift?

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