Cognex Mobile Barcode SDK for iOS

The differences in the capabilities of smartphones as barcode scanning devices result in a user experience different from purpose-built scanners, impacting the design of the mobile barcode scanning application. By following a few simple guidelines, you can develop applications with the cmbSDK that work the same way when using an MX Mobile Terminal or the built-in camera of a mobile device.

• To initiate barcode scanning without a dedicated hardware trigger, see Mobile Device Triggering.
• To aim for barcode scanning with a smartphone that does not have an aimer, see Mobile Device Aiming.
• To choose the most suitable orientation for barcode scanning, see Mobile Device Orientation.
• To reduce the CPU usage of the mobile device when it performs image analysis and barcode decoding, see Optimizing Mobile Device Performance.

Without a hardware trigger, mobile devices must use alternative methods to initiate barcode scanning. The cmbSDK supports three methods to trigger barcode scanning:

• Application or workflow driven trigger: The application code or the business logic/workflow of the application invokes the scanning module. In simple programming terms, it is calling a function like startScanner().
• Virtual trigger: To start or stop the scanning process the application provides a button on the screen. Depending on the application design, you need to press and hold the virtual button to keep the scanner running, this invokes the scanning module.
• Simulated trigger: Press one of the volume buttons to start or stop the scanning process just like when you pull a trigger on a purpose-built scanner.

The built-in camera provides a live-stream preview on the display of the mobile device for barcode aiming. Reposition the mobile device until the barcode appears in the field of view of the built-in camera and the application decodes it. CmbSDK provides a built-in preview control that can be displayed in partial or full screen, and in either portrait or landscape orientation.

The cmbSDK also supports passive aimers: devices attached to the mobile device or its case that use the LED flash of the device as a light source to project an aiming or targeting pattern. The mobile device can project an aimer pattern similar to a purpose-built scanner so live-preview is not needed. However, by using the LED flash as an aimer, general scanning illumination is not available.

In addition to passive aimers, cmbSDK also supports an active aimer that has its own built-in LEDs for illumination and aiming: the MX-100 Barcode Reader. The MX-100 is a mobile device accessory for iOS smartphones attached to the mobile device with a mobile device case. The built-in LED of the MX-100 projects a green dot to help in reading the barcode.

The cmbSDK supports portrait orientation, landscape orientation and auto-rotation for both the presentation of the barcode preview and the scan direction. Mobile devices can scan most barcodes regardless of the orientation of the application and/or the mobile device.

Mobile devices are an ideal platform for barcode decoding. The cmbSDK is optimized for mobile environment, but image analysis and barcode decoding is still a CPU intensive activity. Since these processes share the mobile device's CPU with the mobile operating system (OS), services, and other applications, these processes optimize your barcode scanning application and limit it to only using the features of the cmbSDK that they need.

To optimize your application:

• Enable decoding only for the barcode types the application needs to scan. The cmbSDK supports the decoding of almost 40 different barcode types and subtypes, enabling all results in low performance and unexpected errors.
• Do not enable certain symbologies and/or advanced features at the same time. 
• Optimize your camera resolution. By default, the cmbSDK uses HD images for barcode decoding.
• Use an appropriate decoder effort level. The cmbSDK has a configurable effort level that controls how aggressively it performs image analysis. The cmbSDK uses a default value (level 2) that is sufficient for most barcodes. Using a higher level can result in better decoding of poorer quality barcodes, resulting in slower performance.

No barcode symbologies are enabled by default, when the cmbSDK is initialized for use with the mobile device's built-in camera.

To set up your application to use the iOS cmbSDK:

1. Open XCode and start a new project.

2. Add the following lib and frameworks to your project:

   * SystemConfiguration.framework 
   * AVFoundation.framework
   * CoreGraphics.framework
   * CoreMedia.framework
   * CoreVideo.framework
   * MediaPlayer.framework 
   * Security.framework
   * AudioToolbox.framework 
   * cmbSDK.framework

3. Go to your project's Info.plist file and add the Privacy - Camera Usage Description or NSCameraUsageDescription to display a message about how your application uses the camera of the user's mobile device.

The cmbSDK has been designed to provide a high-level, abstract interface for supported scanning devices. This includes not only the MX series of mobile terminals, but also for applications that intend to use the mobile device camera as the imaging device. The intricacies of communicating with and managing these devices is encapsulated within the SDK itself: leaving the application to just connect to the device of choice, then using it.

The primary interface between your application and a supported barcode scanning device is the CMBReaderDevice class. This class represents the abstraction layer to the device itself, handling all communication as well as any necessary hardware management (e.g., for smartphone scanning).

Perform the following steps to use the cmbSDK: 

1. Initialize a Reader Device for the type of device you want to use (MX reader or camera reader).

2. Connect the Reader Device.

3. Configure the reader (if necessary).

4. Start scanning. 

Initialization, connection, and configuration generally need to be performed only once in your application, except for the following cases:

• An MX reader can become disconnected (times out from disuse,dead battery,etc.). A method has been provided to handle this case, and is discussed in a later section.
• Your application has been designed to allow the user to change devices.The cmbSDK is explicitly designed to support this: your application simply disconnects from the current device and establishes a new connection to a different device. The provided sample application has been written to explicitly demonstrate this capability. 

Initializing the Reader Device for use with an MX mobile terminal like the MX-1000 or MX-1502 is easy: simply create the reader device using the MX device method (it requires no parameters), and set the appropriate delegate (normally self): 

let readerDevice:CMBReaderDevice = CMBReaderDevice.readerOfMX()
readerDevice.delegate = self

CMBReaderDevice *readerDevice = [CMBReaderDevice readerOfMXDevice];
readerDevice.delegate = self;

The availability of the MX mobile terminal can change when the device turns ON or OFF, or if the lightning cable gets connected or disconnected. You can handle those changes using the following CMBReaderDeviceDelegate method.

func availabilityDidChange(ofReader reader: CMBReaderDevice)

- (void)availabilityDidChangeOfReader:(CMBReaderDevice *)reader

Using other Cognex network device

If you want to connect to a Cognex device on the network (e.g handheld or fixed mount) you have to use another framework named as NetworkDiscovery. This framework can be found in the cmbSDK bundle.

Barcode scanning with the built-in camera of the mobile device can be more complex than with an MX mobile terminal. The cmbSDK supports several configurations to provide the maximum flexibility. This includes support of optional, external aimers/illumination, as well as the ability to customize the appearance of the live-stream preview.

To scan barcodes using MX-100 or the built-in camera of the mobile device, initialize the CMBReaderDevice object using the readerOfDeviceCameraWithCameraMode static method. The camera reader has several options when initialized. The following parameters are required:

* CDMCameraMode
* CDMPreviewOption
* UIView

The CameraMode parameter is of the type CDMCameraMode (defined in CDMDataManSystem.h), and it accepts one of the following values:

• kCDMCameraModeNoAimer: This initializes the reader to use a live-stream preview ( on the mobile device screen ) so the user can position the barcode within the camera’s field of view for detection and decoding. Use this mode when the mobile device does not have an aiming accessory.
• kCDMCameraModePassiveAimer: This initializes the reader to use a passive aimer, which is an accessory that is attached to the mobile device or a mobile device case that uses the built-in LED flash of the mobile device as a light source for projecting an aiming pattern. In this mode, no live-stream preview is presented on the device screen, since an aiming pattern will be projected.
• kCDMCameraModeActiveAimer: This initializes the reader to use an active aimer, such as the MX-100, which is an accessory that is attached to the mobile device or a mobile device case. The active aimer has a built in LEDs for projecting an aiming pattern, and for illumination, and are powered by a built in battery. In this mode, no live-stream preview is presented on the device screen, since an aiming pattern will be projected.
• kCDMCameraModeFrontCamera: This initializes the reader to use the front facing camera of the mobile device, if available (not all mobile devices have a front camera). This is an unusual, but possible configuration. Most front-facing cameras do not have auto focus and illumination, and provide significantly lower resolution images. This option should be used with care. In this mode, illumination is not available.

All of the above modes provide the following default settings for the reader:

• The rear camera is used.
• The zoom feature is available and a button to control it is visible on the live-stream preview ( if displayed ).
• The simulated hardware trigger is disabled.
• When startScanning() is called, the decoding process is started. ( Seek CDMPreviewOptionPaused for more details.)

Based on the selected mode, the following additional options and behaviors are set:

• kCDMCameraModeNoAimer ( NoAimer )
  • The live-stream preview is displayed when the startScanning() method is called.
  • Illumination is available and a button to control it is visible on the live-stream preview.
  • If commands are sent to the reader for aimer control, they will be ignored.

• kCDMCameraModePassiveAimer( PassiveAimer )
  • The live-stream preview will not be displayed when the startScanning() method is called.
  • Illumination is not available and the live-stream preview will not have an illumination button.
  • If commands are sent to the reader for illumination control, they will be ignored, since it is assumed in this mode that the built-in LED of the mobile device is being used for the aimer.

• kCDMCameraModeActiveAimer( MX-100 )
  • The live-stream preview will not be displayed when the startScanning() method is called.
  • Illumination is available and if a preview option for camera preview is used, the preview will have an illumination button.
  • If commands are sent to the reader for illumination or aimer control, they will be accepted.

• kCDMCameraModeFrontCamera( FrontCamera )
  • The live-stream preview is displayed when the startScanning() method is called.
  • The front camera is used.
  • Illumination is not available, and the live-stream preview will not have an illumination button. o If commands are sent to the reader for aimer or illumination control, they will be ignored.

The previewOptions parameter (of type CDMPreviewOption, defined in CDMDataManSystem.h) is used to change the reader’s default values or override defaults derived from the selected CameraMode. Multiple options can be specified by OR-ing them when passing the parameter. The available options are the following:

• kCDMPreviewOptionDefaults: Use this option to accept all defaults set by the CameraMode.
• kCDMPreviewOptionNoZoomBtn: This option hides the zoom button on the live-stream preview, preventing a user from adjusting the zoom of the mobile device camera.
• kCDMPreviewOptionNoIllumBtn: This hides the illumination button on the live-stream preview, preventing a user from toggling the illumination.
• kCDMPreviewOptionHwTrigger: This enables a simulated hardware trigger (the volume button) for starting scanning on the mobile device. This button only starts scanning when pressed. It does not need to be held like a more traditional purpose-built scanner’s trigger. Pressing the button a second time does not stop the scanning process.
• kCDMPreviewOptionPaused: If using a live-stream preview, when this option is set, the preview will be displayed when the startScanning() method is called, but the reader will not start decoding (i.e. looking for barcodes) until the user presses the on-screen scanning button to actually start the scanning process.
• kCDMPreviewOptionAlwaysShow: This forces alive-stream preview to be displayed, even if an aiming mode has been selected (e.g. CameraMode == kCDMCameraModePassiveAimer )
• kCDMPreviewOptionPessimisticCaching: Used only when CameraMode == kCDMCameraModeActiveAimer, this will read the settings from the ActiveAimer when the app resumes from background, in case the aimer settings were changed from another app.
• kCDMPreviewOptionHighResolution: This will use the device camera in higher resolution. The default resolution is 1280x720. With this option is enabled, the resolution will be 1920x1080 on devices that support it, and the default one on devices that do not. This can help with scanning small barcodes, but will increase the decoding time since there is a lot more data to process in each frame.
• kCDMPreviewOptionHighFrameRate: This will use the device camera in 60 FPS instead of the default 30, and provide a much smoother camera preview.

The last parameter of type UIView is optional and is used as a container for the camera preview. If the parameter is left nil, a full screen preview will be used.

Examples:

Create a reader with no aimer and a full screen live-stream preview:

let readerDevice:CMBReaderDevice = CMBReaderDevice.readerOfDeviceCamera(with: CDMCameraMode.noAimer, previewOptions:CDMPreviewOption.init(rawValue: 0), previewView:nil)
readerDevice.delegate = self

CMBReaderDevice *readerDevice = [CMBReaderDevice readerOfDeviceCameraWithCameraMode:kCDMCameraModeNoAimer previewOptions:kCDMPreviewOptionDefaults previewView:nil];
readerDevice.delegate = self;

Create a reader with no aimer, no zoom button, and using a simulated trigger:

let readerDevice:CMBReaderDevice = CMBReaderDevice.readerOfDeviceCamera(with: CDMCameraMode.noAimer, previewOptions:[CDMPreviewOption.noZoomBtn, CDMPreviewOption.hwTrigger], previewView:nil)
readerDevice.delegate = self

CMBReaderDevice *readerDevice = [CMBReaderDevice readerOfDeviceCameraWithCameraMode:kCDMCameraModeNoAimer previewOptions:(kCDMPreviewOptionNoZoomBtn | kCDMPreviewOptionHwTrigger) previewView:nil];
readerDevice.delegate = self;

After initializing the Reader Device and setting a delegate to handle responses from the reader, you are ready to connect using connectWithCompletion: 

// Make sure the device is turned ON and ready
if self.readerDevice.availability == CMBReaderAvailibilityAvailable {
    // create the connection between the readerDevice object and device
    self.readerDevice.connect(completion: { (error:Error?) in
        if error != nil {
            // handle connection error
        }
    })
}

// Make sure the device is turned ON and ready
if (readerDevice.availability == CMBReaderAvailibilityAvailable) {
    // create the connection between the readerDevice object and device
    [readerDevice connectWithCompletion:^(NSError *error) {
        if (error) {
            // handle connection error
        }
    }];
}

If everything was done correctly, connectionStateDidChangeOfReader in the delegate will be called, where you can check the connection status in your Reader Device's connectionState parameter. It should be CMBConnectionStateConnected, which means that you have successfully made the connection to the Reader Device, and can begin using the Cognex Mobile Barcode SDK. 

After connecting to the scanning device, you may want (or need) to change some of its settings. The cmbSDK provides a set of high-level, device independent APIs for setting and retrieving the current configuration of the device.

Like in the case of initializing the Reader Device, there are some differences between using an MX reader and the camera reader for scanning. These differences are detailed in the following sections. 

The MX family of mobile terminals provides sophisticated device configuration and management, including saved configurations on the device itself. In general, these devices come from Cognex preconfigured for an exceptional out-of- the-box experience with most symbologies and features ready to use.

When custom reconfiguration is desired, this is typically done using either the DataMan Setup Tool, or the Cognex Quick Setup as these tools can be used to distribute saved configurations easily to multiple devices, thereby greatly simplifying configuration management.

However, it is still possible (and sometimes desirable) for the mobile application itself to configure the MX device: 

• You can have multiple scanning applications, each of which requires a different set of device settings.
• You may simply want to guarantee that the certain options are in a “known” state and not rely on the fact that the device has been pre-configured correctly. 

Much like an MX mobile terminal, the cmbSDK employs a default set of options for barcode reading with the built-in camera of the mobile device, providing a good out-of-box experience. However, there are two important differences to keep in mind:

• The cmbSDK does not implement saved configurations for the camera reader. This means that every time an application that uses the camera reader starts, it starts with its defaults.
• The cmbSDK does not enable any symbologies by default: you as the application programmer must enable all barcode symbologies your application needs to scan. By requiring the application program to explicitly enable only the symbologies it needs, the most optimal scanning performance can be achieved. 

MX-100 is a device-case attachment that provides additional functionalities to the built-in camera, like aiming and better illumination control. Being a hybrid of an MX device and a built in scanner, it has it's own settings for aimer intensity, illumination intensity and aimer modulation stored on the device itself, and the rest of the settings, like symbologies, stored in the cmbSDK.

Here are a few things to keep in mind when using an MX-100 device:

• By default, MX-100 does not require a license to work with the device camera, but one can be generated for tracking purposes, free of charge.
• MX-100 comes pre-configured for a better out-of-the-box experience, and the cmbSDK has the following symbologies enabled by default:
  • Code 39
  • Code 128
  • Databar
  • PDF417
  • QR
  • UPC/EAN
• cmbSDK is extended with a cache mechanism to strengthen optical communication with MX-100. The cache stores all MX-100 settings and it is transparent and available in cmbSDK. Initializing and updating of the cache is the responsibility of cmbSDK itself. Different settings are stored in different cache:
  • Persistent cache: These are settings/values that do not change very often (if at all) and SDK can cache on the iPhone for an extended period of time. These items are the MX-100 Serial number, model number and firmware version. The persistent cache is updated in every 7 days.
  • Session cache: These are settings/values that may change while an application is using an MX-100 (though not likely), but should be read from the MX-100 at least on SDK load/initial connection to the MX-100. These items are: Aimer intensity, Aimer modulation, Aimer timeout, Illumination intensity, Illumination state. When the SDK initially connects to an MX-100, these values are read from the MX-100.
    By default, the session cache will be maintained optimistically for the best performance. By this, we mean that the SDK will assume that another application is not changing the settings of the aimer (SDK only needs to read the aimer's settings one time, when the initial connection is established). If this happens, the cache may become out of sync with the aimer (e.g. another app on the same device changes a setting on the aimer). cmbSDK gives the possibility to handle the session cache pessimistically which means that above written aimer's configuration is loaded again each time when application is resumed. This behavior is accomplished by adding an additional option flag to the camera connector: kCDMPreviewOptionPessimisticCaching.

Individual symbologies can be enabled using the following method of the Reader Device object: 

-(void) setSymbology:(CMBSymbology)symbology 
enabled:(bool)enabled
completion:(void (^)(NSError *error))completionBlock;

All symbologies used for the symbology parameter in this method can be found in CMBReaderDevice.h.

Examples 

self.readerDevice.setSymbology(CMBSymbologyQR, enabled: true, completion: {(_ error: Error?) -> Void in
    if error != nil {
        // Failed to enable that symbology, Possible causes are: reader disconnected, out of battery or cable unplugged, or symbology not supported by the current readerDevice
    }
})

[readerDevice setSymbology:CMBSymbologyQR enabled:YES completion:^(NSError *error){
    if (error) {
        // Failed to enable that symbology, Possible causes are: reader disconnected, out of battery or cable unplugged, or symbology not supported by the current readerDevice
    }
}];

The same method can also be used to turn symbologies off: 

self.readerDevice.setSymbology(CMBSymbologyUpcEan, enabled: false, completion: {(_ error: Error?) -> Void in
    if error != nil {
        // Failed to enable that symbology, Possible causes are: reader disconnected, out of battery or cable unplugged, or symbology not supported by the current readerDevice
    }
})

[readerDevice setSymbology:CMBSymbologyUpcEan enabled:NO completion:^(NSError *error){
    if (error) {
        // Failed to enable that symbology, Possible causes are: reader disconnected, out of battery or cable unplugged, or symbology not supported by the current readerDevice
    }
}];

If your reader device is equipped with illumination lights (e.g. LEDs), you can control whether they are ON or OFF when scanning starts using the following method of your Reader Device object: 

self.readerDevice.setLightsON(true) { (error:Error?) in
    if error != nil {
        // Failed to enable illumination, Possible causes are: reader disconnected, out of battery or cable unplugged, or device doesn't come with illumination lights
    }
}

[readerDevice setLightsON:YES completion:^(NSError *error) {
    if (error) {
        // Failed to enable illumination, Possible causes are: reader disconnected, out of battery or cable unplugged, or device doesn't come with illumination lights
    }
}];

Keep in mind that not all devices and device modes supported by the cmbSDK allow for illumination control. For example, if using the built-in camera in passive aimer mode, illumination is not available since the LED is being used for aiming. 

If built-in camera is used as reader device you have the possibility to configure zoom levels and define the way these zoom levels are used.

There are 3 zoom levels for the phone camera, which are:

• normal: not zoomed (100%)
• level 1 zoom (default 200% on iOS)
• level 2 zoom (default 400% on iOS)

You can define these zoom levels with "SET CAMERA.ZOOM-PERCENT [100-MAX] [100-MAX]" command. It configures how far the two levels will zoom in percentage. 100 is without zoom, and MAX (goes up to 1000) will zoom as far as the device is capable of. First argument is used for setting level 1 zoom, and the second for level 2 zoom.

When you want to check current setting, you can do this with the "GET CAMERA.ZOOM-PERCENT" that returns two values: level 1 and level 2 zoom.

Example

readerDevice.dataManSystem()?.sendCommand("SET CAMERA.ZOOM-PERCENT 250 500")

[readerDevice.dataManSystem sendCommand:@"SET CAMERA.ZOOM-PERCENT 250 500"];

here is another command that sets which zoom level you want to use or returns the actual setting: "GET/SET CAMERA.ZOOM 0-2".

Possible values for the SET command are:

• 0 - normal (un-zoomed)
• 1 - zoom at level 1
• 2 - zoom at level 2

You can call this command before scanning or even during scanning, the zoom goes up to the level that was configured.

If the scanning is finished, the values is reset to normal behavior (0).

Example

readerDevice.dataManSystem()?.sendCommand("SET CAMERA.ZOOM 2")

[readerDevice.dataManSystem sendCommand:@"SET CAMERA.ZOOM 2"];

When using the Mobile Camera, cmbSDK allows you to see the Camera Preview inside a preview container or in full screen. This preview also contains an overlay, which can be customized in many ways. The cmbSDK camera overlay is built from buttons for zoom, flash and closing the scanner (in full screen), a progress bar indicating the scan timeout, and lines on the corners of the camera preview.

To use the legacy camera overlay, which was used in the cmbSDK v2.0.x and the ManateeWorks SDK, use this property from MWOverlay before initializing the readerDevice:

MWOverlay.setOverlayMode(Int32(OM_LEGACY.rawValue))

[MWOverlay setOverlayMode:OM_LEGACY];

The LEGACY overlay has limited customizability, so it is preferred to use the CMB overlay.

When using the CMB overlay, you can copy the layout files found in the Resources/layout directory into your project and modify them as you like. The files are: CMBScannerPartialView.xib used when the scanner is started inside a container (partial view), and CMBScannerView.xib when the scanner is started in full screen.
After copying the layout that you need, or both layouts, you can modify them, for example by changing the sizes, positions or color of the views, removing views and even add your own views, like an overlay image. The views that are used by the cmbSDK (zoom, flash, close buttons, the view used for drawing lines on the corners, and the progress bar) are accessed by the sdk using the Tag attribute, so while you can change everything about those views, make sure the Tag attribute remains unchanged, otherwise the cmbSDK will not be able to recognize those views and continue to function as if those views were removed.

Both the CMB and the LEGACY overlay allow you to change the images used on the zoom and flash buttons. To do that, first copy the assets folder MWBScannerImages.xcassets from the Resources dir into your project. In XCode you can look at the images contained in this assets folder, and replace them with your own while keeping the image names unchanged.

Both the CMB and the LEGACY overlay allow you to change the color and width of the rectangle that is displayed when a barcode is detected. Here's an example on how to do that:

MWOverlay.setLocationLineUIColor(UIColor.yellow)
MWOverlay.setLocationLineWidth(5)

[MWOverlay setLocationLineUIColor:UIColor.yellowColor];
[MWOverlay setLocationLineWidth:5];

Every Cognex scanning device implements DataMan Control Commands (DMCC), a method for configuring and controlling the device. Virtually every feature of the device can be controlled using this text based language. The API provides a method for sending DMCC commands to the device. Commands exist both for setting and querying configuration properties.

Appendix A includes the complete DMCC reference for use with the camera reader. DMCC commands for other supported devices (e.g. the MX-1000) are included with the documentation of that particular device.
Appendix B provides the default values for the camera reader’s configuration settings as related to the corresponding DMCC setting.
The following examples show different DMCC commands being sent to the device for more advanced configuration. Change the scan direction to omnidirectional: 

self.readerDevice.dataManSystem()?.sendCommand("SET DECODER.1D-SYMBOLORIENTATION 0", withCallback: { (response:CDMResponse?) in
    if response?.status == DMCC_STATUS_NO_ERROR {
        // Command was executed successfully
    } else {
        // Command failed, handle errors here
    }
})

[readerDevice.dataManSystem sendCommand:@"SET DECODER.1D-SYMBOLORIENTATION 0" withCallback:^(CDMResponse *response){
    if (response.status == DMCC_STATUS_NO_ERROR) {
        // Command was executed successfully
    } else {
        // Command failed, handle errors here
    }
}];

Change the scanning timeout of the live-stream preview to 10 seconds: 

self.readerDevice.dataManSystem()?.sendCommand("SET DECODER.MAX-SCAN-TIMEOUT 10", withCallback: { (response:CDMResponse?) in
    if response?.status == DMCC_STATUS_NO_ERROR {
        // Command was executed successfully
    } else {
        // Command failed, handle errors here
    }
})

[readerDevice.dataManSystem sendCommand:@"SET DECODER.MAX-SCAN-TIMEOUT 10" withCallback:^(CDMResponse *response){
    if (response.status == DMCC_STATUS_NO_ERROR) {
        // Command was executed successfully
    } else {
        // Command failed, handle errors here
    }
}];

Get the type of the connected device: 

self.readerDevice.dataManSystem()?.sendCommand("GET DEVICE.TYPE", withCallback: { (response:CDMResponse?) in
    if response?.status == DMCC_STATUS_NO_ERROR {
        // Command was executed successfully
        let deviceType:String = response?.payload
    } else {
        // Command failed, handle errors here
    }
})

[readerDevice.dataManSystem sendCommand:@"GET DEVICE.TYPE" withCallback:^(CDMResponse *response){
    if (response.status == DMCC_STATUS_NO_ERROR) {
        // Command was executed successfully
        NSString *deviceType = response.payload;
    } else {
        // Command failed, handle errors here
    }
}];

The cmbSDK includes a method for resetting the device to its default settings. In the case of an MX mobile terminal, this is the configuration saved by default (not the factory defaults), while in the case of the built-in camera, these are the defaults identified in Appendix B, where no symbologies will be enabled. This method is the following: 

self.readerDevice.resetConfig { (error:Error?) in
    if error != nil {
        // Failed to reset configuration, Possible causes are: reader disconnected, out of battery or cable unplugged
    }
}

[readerDevice resetConfigWithCompletion:^(NSError *error) {
    if (error) {
        // Failed to reset configuration, Possible causes are: reader disconnected, out of battery or cable unplugged
    }
}];

With a properly configured reader, you are now ready to scan barcodes. This is simply accomplished by calling the startScanning() method from your Reader Device object. What happens next is based on the type of Reader Device and how it has been configured, but in general: 

• If using an MXreader, the user can now press a trigger button on the device to turn the scanner on and read a barcode.
• If using the camera reader, the cmbSDK starts the camera, displays the configured live-stream preview,and begins analyzing the frames from the video stream, looking for a configured barcode symbology. 

Scanning stops under one of the following conditions: 

• The reader found and decodeda barcode.
• The user released the trigger or pressed the stop button on the live-stream preview screen.
• The camera reader timed out with out finding a barcode.
• The application program itself calls the stopScanning() method. 

When a barcode is decoded successfully (the first case), you will receive a CMBReadResults array in your Reader Device's delegate using the following CMBReaderDeviceDelegate method: 

func didReceiveReadResult(fromReader reader: CMBReaderDevice, results readResults: CMBReadResults!)

- (void)didReceiveReadResultFromReader:(CMBReaderDevice *)reader results:(CMBReadResults *)readResults;

 The following is an example to simply display a ReadResult after scanning a barcode: 

func didReceiveReadResult(fromReader reader: CMBReaderDevice, results readResults: CMBReadResults!) {
    if readResults.readResults.count > 0 {
        let readResult:CMBReadResult = readResults.readResults?.first as! CMBReadResult
        if readResult.image != nil {
            self.ivPreview.image = readResult.image
        }
        if readResult.readString != nil {
            self.lblCode.text = readResult.readString
        }
    }
}

- (void)didReceiveReadResultFromReader:(CMBReaderDevice *)reader results:(CMBReadResults *)readResults {
    if (readResults.readResults.count > 0) {
        CMBReadResult *readResult = readResults.readResults.firstObject;
        if (readResult.image) {
            self.ivPreview.image = readResult.image;
        }
        if (readResult.readString) {
            self.lblCode.text = readResult.readString;
        }
    }
}

In the example above, ivPreview is an UIImageView used to display an image of the barcode that was scanned, and lblCode is a UILabel used to show the result from the barcode. You can also use the BOOL from readResult.goodRead to check whether the scan was successful or not. 

When a barcode is successfully read, a CMBReadResult object is created and returned by the didReceiveReadResultFromReader:results: method. In case of having multiple barcodes successfully read on a single image/frame, multiple CMBReadResult objects are returned. This is why the CMBReadResults class has an array of CMBReadResult objects containing all results.

The CMBReadResult class has properties describing the result of a barcode read:

• goodRead (BOOL): tells whether the read was successful or not
• readString (NSString): the decoded barcode as a string
• image (UIImage): the image/frame that the decoder has processed
• imageGraphics (NSData): the boundary path of the barcodeas SVG data
• XML (NSData): the raw XML that the decoder returned
• symbology (CMBSymbology): the symbology type of the barcode.This enum is defined in CMBReaderDevice.h.

When a scanning ends with no successful read, a CMBReadResult is returned with the goodRead property set to false. This usually happens when scanning is canceled or timed out.

To enable the image and imageGraphics properties being filled in the CMBReadResult object, you have to set the corresponding imageResultEnabled and/or SVGResultEnabled properties of the CMBReaderDevice object.

To see an example on how the image and SVG graphics are used and displayed in parallel, refer to the sample applications provided in the SDK package.

To access the raw bytes from the scanned barcode, you can use the XML property. The bytes are stored as a Base64 String under the "full_string" tag. Here's an example how you can use the iOS XML parser to extract the raw bytes from the XML property.

Parsing the XML and extracting the Base64 String is done using the XMLParserDelegate delegate. Add this delegate and the following methods from it in your ViewController:

// XMLParserDelegate
var currentElement = ""
var base64String = ""
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
    currentElement = elementName
}

func parser(_ parser: XMLParser, foundCharacters string: String) {
    if currentElement == "full_string" {
        base64String = string
    }
}

#pragma NSXMLParserDelegate
NSString *currentElement;
NSString *base64String;
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary<NSString *,NSString *> *)attributeDict {
    currentElement = elementName;
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
    if ([currentElement isEqualToString:@"full_string"]) {
        base64String = string;
    }
}

After you have set the XMLParserDelegate to extract the base64 string from the XML result, you need to create a XMLParser object and parse the result.xml using this delegate. This can be done when receiving the scan result in the CMBReaderDeviceDelegate, or when accessing a CMBReadResult object. Here's how you can get the raw bytes using the delegate that you created earlier:

let xmlParser:XMLParser = XMLParser.init(data: result.xml)
xmlParser.delegate = self
if xmlParser.parse() {
    // Access the raw bytes via this variable
    let bytes:Data? = Data.init(base64Encoded: base64String)
}

NSXMLParser *xmlParser = [NSXMLParser.alloc initWithData:result.XML];
xmlParser.delegate = self;
if ([xmlParser parse]) {
    // Access the raw bytes via this variable
    NSData *bytes = [NSData.alloc initWithBase64EncodedString:base64String options:0];
}

By default, the image and SVG results are disabled, which means that when scanning, the CMBReadResults will not contain any data in the corresponding properties.

To enable image results, set the imageResultEnabled property from the CMBReaderDevice class by using the following method: 

self.readerDevice.imageResultEnabled = true

[readerDevice setImageResultEnabled:YES];

To enable SVG results, set the imageResultEnabled property from the CMBReaderDevice class by using the following method: 

self.readerDevice.svgResultEnabled = true

[readerDevice setSVGResultEnabled:YES];

There may be cases when a device disconnects due to low battery condition or manual cable disconnection. These cases can be detected by the connectionStateDidChangeOfReader callback of the CMBReaderDeviceDelegate.

After you return to your application from inactive state, the reader device remains initialized, but not connected. This means there is no need for reinitializing the SDK, but you will need to re-connect.

Some iOS versions will send a "Availability" notification when resuming the application that the External Accessory is available. You can use this in the CMBReaderDeviceDelegate's method: (void)availabilityDidChangeOfReader:(CMBReaderDevice *)reader. In it, when the reader becomes available, you can connect to it.

For example:

func availabilityDidChange(ofReader reader: CMBReaderDevice) {
    if (reader.availability == CMBReaderAvailibilityAvailable) {
        readerDevice.connect(completion: { error in
            if error != nil {
                // handle connection error
            }
        })
    }
}

- (void)availabilityDidChangeOfReader:(CMBReaderDevice *)reader {
    if (readerDevice.availability == CMBReaderAvailibilityAvailable) {
        [readerDevice connectWithCompletion:^(NSError *error) {
            if (error) {
               // handle connection error
            }
        }];
    }
}

Some iOS versions do not report availability change on resume, so you will have to handle this manually. For this, you will have to add an observer for "UIApplicationDidBecomeActiveNotification" and do some checks before connecting, so you don't connect while the reader is already in "connecting" or "connected" state. For example:

override func viewDidLoad() {
    super.viewDidLoad()
    // Reconnect when app resumes
    NotificationCenter.default.addObserver(self, selector: #selector(self.appBecameActive), name:NSNotification.Name.UIApplicationDidBecomeActive, object: nil)
}

// handle app resume
func appBecameActive() {
    if readerDevice != nil
        && readerDevice.availability == CMBReaderAvailibilityAvailable
        && readerDevice.connectionState != CMBConnectionStateConnecting && readerDevice.connectionState != CMBConnectionStateConnected {
        readerDevice.connect(completion: { error in
            if error != nil {
                // handle connection error
            }
        })
    }
}

- (void)viewDidLoad {
     // Reconnect when app resumes
     [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(appBecameActive)
                                                     name:UIApplicationDidBecomeActiveNotification object:nil];
}

// handle app resume
-(void) appBecameActive {
    if (readerDevice != nil
        && readerDevice.availability == CMBReaderAvailibilityAvailable
        && readerDevice.connectionState != CMBConnectionStateConnecting && readerDevice.connectionState != CMBConnectionStateConnected) {
        [readerDevice connectWithCompletion:^(NSError *error) {
            if (error) {
                // handle connection error
            }
        }];
    }
}

The following table lists the various DMCC commands supported by the cmbSDK when using the built-in camera for barcode scanning. 

The following table lists the defaults the SDK uses on startup for the camera reader. 

Appendix B - Camera Reader Defaults 

Observe these precautions when installing the Cognex product, to reduce the risk of injury or equipment damage:

• To reduce the risk of damage or malfunction due to over-voltage, line noise, electrostatic discharge (ESD), power surges, or other irregularities in the power supply, route all cables and wires away from high-voltage power sources.
• Changes or modifications not expressly approved by the party responsible for regulatory compliance could void the user’s authority to operate the equipment.
• Cable shielding can be degraded or cables can be damaged or wear out more quickly if a service loop or bend radius is tighter than 10X the cable diameter. The bend radius must begin at least six inches from the connector.
• This device should be used in accordance with the instructions in this manual.
• All specifications are for reference purpose only and may be changed without notice.