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In this guide you will learn step-by-step how to add Barcode Selection to your application.

The general steps are:

  • Creating a new Data Capture Context instance
  • Configuring the Barcode Selection settings
  • Creating a new Barcode Selection mode instance
  • Registering the listener to receive scan events:
    • Processing the successful scans according to your application’s needs, e.g. by looking up information in a database
    • Deciding whether more codes will be scanned, or the scanning process should be stopped
  • Obtaining the camera instance and set as frame source

Prerequisites​

Before starting with adding a capture mode, make sure that you have a valid Scandit Data Capture SDK license key and that you added the necessary dependencies. If you have not done that yet, check out this guide.

note

You can retrieve your Scandit Data Capture SDK license key, by signing in to your account Dashboard.

Create a Data Capture Context​

The first step to add capture capabilities to your application is to create a new Data Capture Context. The context expects a valid Scandit Data Capture SDK license key during construction.

self.context = DataCaptureContext(licenseKey: "-- ENTER YOUR SCANDIT LICENSE KEY HERE --")

Configure the Barcode Selection Mode​

Barcode selection is orchestrated by the SDCBarcodeSelection data capture mode. It is configured via SDCBarcodeSelectionSettings and allows you to register one or more listeners for when new codes have been selected.

Here we setup barcode scanning for the desired barcode symbologies. The list of symbologies to enable is highly application specific, and we recommend that you only enable the list of symbologies your application requires:

let settings = BarcodeSelectionSettings()
settings.set(symbology: .code128, enabled: true)
settings.set(symbology: .ean8, enabled: true)
settings.set(symbology: .upce, enabled: true)
settings.set(symbology: .ean13UPCA, enabled: true)

And then create a SDCBarcodeSelection instance with the Data Capture Context and the settings initialized in the previous step:

let barcodeSelection = BarcodeSelection(context: context, settings: settings)

Selection Types​

The behavior of Barcode Selection can be changed by using a different selection type. This defines the method used by SDCBarcodeSelection to select codes. There are two types:

SDCBarcodeSelectionTapSelection​

You can select to automatically freeze the camera preview to make the selection easier via SDCBarcodeSelectionTapSelection.freezeBehavior.

Using SDCBarcodeSelectionTapSelection.tapBehavior you can further decide if a second tap on a barcode means that the barcode is unselected or if it is selected another time (increasing the counter).

SDCBarcodeSelectionAimerSelection​

With this selection mode it is possible to choose between two different selection strategies:

Single Barcode Selection​

If you want to automatically select a barcode when it is the only one on screen, turn on SDCBarcodeSelectionSettings.singleBarcodeAutoDetection:

settings.singleBarcodeAutoDetection = true

Registering the Listener​

To get informed whenever a new code has been recognized, add a SDCBarcodeSelectionListener, implementing the listener methods to suit your application’s needs.

First conform to the SDCBarcodeSelectionListener protocol. For example:

extension ScanViewController: BarcodeSelectionListener {
  func barcodeSelection(_ barcodeSelection: BarcodeSelection,
                        didUpdateSelection session: BarcodeSelectionSession,
                        frameData: FrameData?) {
      let newlySelectedBarcodes = session.newlySelectedBarcodes
      // Do something with the newly selected barcodes.
  }
}

Then register the listener to the SDCBarcodeSelection instance:

barcodeSelection.addListener(self)

Obtaining the Camera Instance and Set as Frame Source​

The data capture context supports using different frame sources to perform recognition, here we assume that you will use the built-in camera of the device.

note

In iOS, the user must explicitly grant permission for each app to access the camera. Your app needs to provide static messages to display when the system asks for camera permission. To do that include the NSCameraUsageDescription key in your app’s Info.plist file.

When using the built-in camera there are recommended settings for each capture mode. These should be used to achieve the best performance and user experience for the respective mode:

let cameraSettings = BarcodeSelection.recommendedCameraSettings

// Depending on the use case further camera settings adjustments can be made here.

let camera = Camera.default
camera?.apply(cameraSettings)

Because the frame source is configurable, the data capture context must be told which frame source to use. This is done with a call to SDCDataCaptureContext.setFrameSource:completionHandler::

context.setFrameSource(camera)

The camera is off by default and must be turned on. This is done by calling:

camera?.switch(toDesiredState: .on)

Disabling Barcode Selection​

To disable barcode selection, for instance when the selection is complete, set SDCBarcodeSelection.enabled to NO.

The effect is immediate, no more frames will be processed after the change. However, if a frame is currently being processed, this frame will be completely processed and deliver any results/callbacks to the registered listeners.

Note that disabling the capture mode does not stop the camera, the camera continues to stream frames until it is turned off:

camera?.switch(toDesiredState: .off)