Scan barcodes with ML Kit on iOS

Page Summary

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• ML Kit can be used to recognize and decode various barcode formats in images.

• Input images should have sufficient resolution and focus for accurate barcode scanning.

• For real-time applications, optimize performance by adjusting image capture resolution and using the synchronous API.

• Configure the barcode scanner to scan specific formats for improved speed.

• Access barcode data like bounding coordinates, raw value, and parsed information based on the value type.

You can use ML Kit to recognize and decode barcodes.

Try it out

• Play around with the sample app to see an example usage of this API.

Before you begin

1. Include the following ML Kit pods in your Podfile:

   pod 'GoogleMLKit/BarcodeScanning', '8.0.0'
   

2. After you install or update your project's Pods, open your Xcode project using its .xcworkspace. ML Kit is supported in Xcode version 12.4 or greater.

Input image guidelines

• For ML Kit to accurately read barcodes, input images must contain barcodes that are represented by sufficient pixel data.

  The specific pixel data requirements are dependent on both the type of barcode and the amount of data that's encoded in it, since many barcodes support a variable size payload. In general, the smallest meaningful unit of the barcode should be at least 2 pixels wide, and for 2-dimensional codes, 2 pixels tall.

  For example, EAN-13 barcodes are made up of bars and spaces that are 1, 2, 3, or 4 units wide, so an EAN-13 barcode image ideally has bars and spaces that are at least 2, 4, 6, and 8 pixels wide. Because an EAN-13 barcode is 95 units wide in total, the barcode should be at least 190 pixels wide.

  Denser formats, such as PDF417, need greater pixel dimensions for ML Kit to reliably read them. For example, a PDF417 code can have up to 34 17-unit wide "words" in a single row, which would ideally be at least 1156 pixels wide.

• Poor image focus can impact scanning accuracy. If your app isn't getting acceptable results, ask the user to recapture the image.

• For typical applications, it's recommended to provide a higher resolution image, such as 1280x720 or 1920x1080, which makes barcodes scannable from a larger distance away from the camera.

  However, in applications where latency is critical, you can improve performance by capturing images at a lower resolution, but requiring that the barcode make up the majority of the input image. Also see Tips to improve real-time performance.

1. Configure the barcode scanner

For example, to scan only Aztec code and QR codes, build a BarcodeScannerOptions object as in the following example:

let format = .all
let barcodeOptions = BarcodeScannerOptions(formats: format)
  

MLKBarcodeScannerOptions *options =
  [[MLKBarcodeScannerOptions alloc]
   initWithFormats: MLKBarcodeFormatQRCode | MLKBarcodeFormatAztec];

2. Prepare the input image

Create a VisionImage object using a UIImage or a CMSampleBuffer.

If you use a UIImage, follow these steps:

• Create a VisionImage object with the UIImage. Make sure to specify the correct .orientation.

  Swift

  let image = VisionImage(image: UIImage)
  visionImage.orientation = image.imageOrientation

  Objective-C

  MLKVisionImage *visionImage = [[MLKVisionImage alloc] initWithImage:image];
  visionImage.orientation = image.imageOrientation;

If you use a CMSampleBuffer, follow these steps:

• Specify the orientation of the image data contained in the CMSampleBuffer.

  To get the image orientation:

  Swift

  func imageOrientation(
    deviceOrientation: UIDeviceOrientation,
    cameraPosition: AVCaptureDevice.Position
  ) -> UIImage.Orientation {
    switch deviceOrientation {
    case .portrait:
      return cameraPosition == .front ? .leftMirrored : .right
    case .landscapeLeft:
      return cameraPosition == .front ? .downMirrored : .up
    case .portraitUpsideDown:
      return cameraPosition == .front ? .rightMirrored : .left
    case .landscapeRight:
      return cameraPosition == .front ? .upMirrored : .down
    case .faceDown, .faceUp, .unknown:
      return .up
    }
  }
        

  Objective-C

  -