Getting Started with React Native Capture SDK¶

Requirements¶

The Socket Mobile Capture SDK uses Bluetooth Classic for the barcode scanner products and Bluetooth Low Energy (BLE) for the Contactless Reader/Writer products (Socket Mobile D600, S550).

Even though the React Native Capture SDK allows to develop an app to run on iOS and Android the underlying Capture architecture on these 2 platforms is different.

On Android there is a service embedded in the Socket Mobile Companion app that is required in order to connect the Socket Mobile device to the Android host.

On iOS the communication with the Socket Mobile devices are embedded in the React Native Module therefore adding more configuration to be taken care of in the application itself.

Requirements for iOS platform

For applications that need to work with barcode scanners, make sure the following requirements are met:

Your iOS application needs to be registered in our Apple MFI Approved Application list before submitting your application to the Apple Store. It will not pass the Apple Store review if this is not done.
Your application must have the string com.socketmobile.chs in the Supported External Protocol setting.
Your application must add some security descriptions for the Bluetooth permissions as shown here:

Requirements for both iOS and Android platforms

Your application will need a SocketMobile AppKey. Follow the link to create an AppKey. AppKeys can be generated online and at no additional cost beyond the nominal one time registration fee. The AppKey is validated by the SDK library on the device, no internet connection is required. Note: You don’t need to create your own AppKey to compile and run the sample apps.
The scanner needs to be paired with your devices in Application Mode. This can be done using Socket Mobile Companion app which can be downloaded from the App Store .
Try our React Native sample app Single Entry React Native.

SDK Installation (Latest)¶

Given the need to privatize our SDKs, we will no longer be referring to this module as an NPM dependency with a version number. In order to use private packages on NPM we would need…

A _paid_ account, and…
To pay for each user we add outside of the organization (and yet another access token for devs to use).

In lieu of this option, by referencing the SDK by way of the new [private gitlab repo](https://sdk.socketmobile.com/capture/react-native-capturesdk), we can essentially keep the dependency private and re-use the group access token that developers would need to use in order to clone the repo. It is a read only credential that will still allow them to use our SDK without having to create/be given yet another access token.

The syntax for adding the dependency in your package.json file can be seen below.

``` “dependencies”: {

“react”: “18.2.0”, “react-native”: “0.68.2”, “react-native-capturesdk”: “https://oauth2:glpat-HQthS5rpDAcLHtngKxym@sdk.socketmobile.com/capture/react-native-capturesdk.git”

},

```

Note: When using the latest, the new SDK package name is react-native-capturesdk. For deprecated usage, please use the original name react-native-capture.

SDK Installation (Deprecated)¶

The React Native Capture SDK is released as a NPM (Node Package Manager) package.

Using yarn

yarn add react-native-capture

Using npm

npm install --save react-native-capture

Using Capture SDK¶

First, once the NPM package has been installed CaptureSDK can be imported as shown below:

Here are the usual steps to follow:

Open Capture with the App credentials and provide event handler function
Handle device arrival and open the device in the event handler function
Handle device removal and close the device in the event handler function
Handle decoded data in the event handler function

Opening Capture with App credentials

The React Native Capture SDK is an extension of the CaptureJS SDK. The main difference is the first instance that use CaptureRn instead of Capture:

const capture = new CaptureRn();
const appInfo = {
appId: 'web:com.socketmobile.SingleEntryRN',
developerId: 'bb57d8e1-f911-47ba-b510-693be162686a',
appKey:
  'MC4CFQCcoE4i6nBXLRLKVkx8jwbEnzToWAIVAJdfJOE3U+5rUcrRGDLuXWpz0qgu',
};
capture
.open(appInfo, onCaptureEvent)
.then(() => {
  setStatus('capture open success');
})
.catch(err => {
  myLogger.error(err);
  setStatus(`failed to open Capture: ${err}`);
  // this is mostly for Android platform which requires
  // Socket Mobile Companion app to be installed
  if (err === SktErrors.ESKT_UNABLEOPENDEVICE) {
    setStatus('Is Socket Mobile Companion app installed?');
  }
});

Handle device arrival and open the device

When the application receives a Device Arrival notification, it can create a new CaptureRn object that represents the new device.

The application opens the device by passing GUID and the main CaptureRn reference as arguments of the device open function.

Opening the device allows to receive the decoded data from this device.

Note

the device GUID changes everytime the device connects. It identifies a connection session with a device.

Note

If a Socket Mobile device is already connected to the host prior to the app opening Capture SDK, the device arrival notificaiton will still be sent to make the application aware that the device is connected.

Note

The second argument of the onCaptureEvent, handle, is optional. It could be used to identify which Capture object is the source of the notification.

In the onCaptureEvent callback passed when opening Capture you could have code similar to this handling the device arrival notification:

const onCaptureEvent = (e, handle) => {
  if (!e) {
    return;
  }

  switch (e.id) {
    // **********************************
    // Device Arrival Event
    //   a device needs to be opened in
    //   to receive the decoded data
    //  e = {
    //    id: CaptureEventIds.DeviceArrival,
    //    type: CaptureEventTypes.DeviceInfo,
    //    value: {
    //      guid: "b876d9a8-85b6-1bb5-f1f6-1bb5d78a2c6e",
    //      name: "Socket S740 [E2ABB4]",
    //      type: CaptureDeviceType.ScannerS740
    //    }
    //  }
    // **********************************
    case CaptureEventIds.DeviceArrival:
      const newDevice = new CaptureRn();
      const {guid, name} = e.value;
      newDevice
        .openDevice(guid, capture)
        .then(result => {
          setStatus(`result of opening ${e.value.name} : ${result}`);
          setDevices(prevDevices => {
            prevDevices = prevDevices || [];
            prevDevices.push({
              guid,
              name,
              handle: newDevice.clientOrDeviceHandle,
              device: newDevice,
            });
            return [...prevDevices];
          });
        })
        .catch(err => {
          setStatus(`error opening a device: ${err}`);
        });
      break;
../..

Handle device removal and close the device

The device removal occurs when the Socket Mobile is no longer connected to the host. It is recommended to close it.

In the onCaptureEvent callback passed when opening Capture you could have code similar to this:

// **********************************
// Device Removal Event
//   it is better to close the device
//  e = {
//    id: CaptureEventIds.DeviceRemoval,
//    type: CaptureEventTypes.DeviceInfo,
//    value: {
//      guid: "b876d9a8-85b6-1bb5-f1f6-1bb5d78a2c6e",
//      name: "Socket S740 [E2ABB4]",
//      type: CaptureDeviceType.ScannerS740
//    }
//  }
// **********************************
case CaptureEventIds.DeviceRemoval:
  const removeDevice = devices.find(d => d.guid === e.value.guid);
  if (!removeDevice) {
    return;
  }
  setDevices(prevDevices => {
    prevDevices = prevDevices.filter(d => d.guid !== e.value.guid);
    return prevDevices;
  });
  removeDevice.device
    .close()
    .then(result => {
      setStatus(`result of closing ${removeDevice.name}: ${result}`);
    })
    .catch(err => {
      setStatus(`error closing a device: ${err}`);
    });
  break;

  ../..

Handle decoded data in the event handler function

Each time a Socket Mobile device is successful at reading a barcode or an NFC tag, the decoded data notification is sent and can be handled as shown here:

Note

Capture does not interpret the decoded data, only the application knows how to interpret it. For demonstration purpose the decoded data can be displayed with the help of a function like this:

function arrayToString(dataArray) {
    return String.fromCharCode.apply(null, dataArray);
}

// **********************************
// Decoded Data
//   receive the decoded data from
//   a specific device
//  e = {
//    id: CaptureEventIds.DecodedData,
//    type: CaptureEventTypes.DecodedData,
//    value: {
//      data: [55, 97, 100, 57, 53, 100, 97, 98, 48, 102, 102, 99, 52, 53, 57, 48, 97,
//             52, 57, 54, 49, 97, 51, 49, 57, 50, 99, 49, 102, 51, 53, 55],
//      id: CaptureDataSourceID.SymbologyQRCode,
//      name: "QR Code"
//    }
//  }
// **********************************
case CaptureEventIds.DecodedData:
  const deviceSource = devices.find(d => d.handle === handle);
  if (deviceSource) {
    setStatus(`decoded data from: ${deviceSource.name}`);
  }
  if (lastDecodedData.length) {
    setDecodedDataList(prevList => {
      const newDecodedData = {...lastDecodedData};
      newDecodedData.id = dataId++;
      return [newDecodedData, ...prevList];
    });
  }
  lastDecodedData = {
    data: arrayToString(e.value.data),
    length: e.value.data.length,
    name: e.value.name,
  };
  setDecodedData(lastDecodedData);
  break;

  ../..

Using useRef React Hook You might encounter memory or state reference issues in your React Native app when trying to access them within the :code-block:`onCaptureEvent` callback that is passed to the :code-block:`CaptureRn` instance. This is likely because :code-block:`onCaptureEvent` is not actually invoked by the component itself but rather as a side effect/listener that is operating in the context of the :code-block:`CaptureRn` instance. This leads to complex data structures in state, such as arrays and objects, not being reliably accessible.

A workaround to this is to use the :code-block:`useRef` hook. This will allow you to store various state values in an actual reference value related to the component. This reference can then be accessed in the context that :code-block:`onCaptureEvent` is operating in. You can add by including it in the general import at the top of your component.

Then you can use it after you declare your React Hook state values.

Issues with Hot Reload for iOS Right now there is an issue when using an iOS device where the hot reload provided by react doesn’t lead to the full chain of events of the previous app state. For example, if you opened capture, then connected a device, if you were to save your code or reload your app entirely, then the only event picked up on the device will be the open capture.

We are currently working to resolve this. In the meantime, you will need to disconnect and reconnect your scanner (including SocketCam). This might result in an error, especially after a full reload, in the sample app saying “no matching devices found for DEVICE_NAME”. This is normal because the device arrival wasn’t triggered so while the device is still connected in the background, the UI doesn’t register it.

So when you disconnect it, a remove device event is triggered and picked up by the UI, but the function that finds and removes the device from the device list will throw an error saying the device couldn’t be found. At the moment this is normal. Just turn on your device or re-enable SocketCam and the new device arrival will be detected.

While this work around is not the most convenient for development, it has no effect on production. Android development and production are also not affected.