User Level
==========
The User Level regroups the features that have an impact on the user experience.

The Socket barcode scanners provide ways to notify the user when the barcode
read is correct or incorrect without the need for the user to check the screen
of the host.

The scanner has 3 types of feedback: sound, LED and vibrate.

For example, depending on the environment, you may want to turn off the sound
and use only the vibration.

Here are some examples on how to use these feedback mechanisms.

Turning off the Sound
^^^^^^^^^^^^^^^^^^^^^
Turning off the good read sound is a simple 2 step process. Since this setting
is persistent on the scanner, it is best to first read this setting when the
scanner connects and depending on its state, either change it or just continue
on.

Let's imagine we would like to offer to the user a switch button in the UI to
turn on or off the beep when scanning a barcode.

The ``didNotifyArrivalForDevice`` delegate is used to request the actual state
of the scanner local decode action so the switch to configure this setting could
be positioned accordingly to the actual state of the scanner decode action.

The code might look like this::

  -(void)didNotifyArrivalForDevice:(SKTCaptureHelperDevice*) device withResult:(SKTResult) result{
      NSLog(@"Receive device arrival for %@", device.friendlyName);
      dispatch_async(dispatch_get_main_queue(), ^{
          _statusLabel.text = device.friendlyName;
      });

      // ask for the device Battery Level
      [device getBatteryLevelWithCompletionHandler:^(SKTResult result, NSInteger levelInPercentage) {
          [self displayBatteryLevel: levelInPercentage];
      }];

      [device getDecodeActionWithCompletionHandler:^(SKTResult result, SKTCaptureLocalDecodeAction decodeAction) {
          if (result == SKTCaptureE_NOERROR){
              device.localDecodeAction = decodeAction;
              dispatch_async(dispatch_get_main_queue(), ^{
                  if((decodeAction&SKTCaptureLocalDecodeActionBeep) == SKTCaptureLocalDecodeActionBeep){
                      [[self beepSwitch]setOn: TRUE];
                  }
                  else {
                      [[self beepSwitch]setOn: FALSE];
                  }
                  [[self beepSwitch]setEnabled:TRUE];
              });
          }
      }];
      _lastDeviceConnected = device;
  }

.. note::
  The completion handler of ``getDecodeActionWithCompletionHandler`` has the code
  refreshing the UI in the main dispatch queue using the
  ``dispatch_async(dispatch_get_main_queue(), ^{...});`` function to have the
  block code running in the context of the main thread.


Then the handler of the ``beepSwitch`` switch is in charge of turning off or
on the beep when the scanner reads a barcode and the code could look like this::

  - (IBAction)didChangeBeepSwitch:(id)sender {
      SKTCaptureLocalDecodeAction decodeAction = _lastDeviceConnected.localDecodeAction;
      if( [[self beepSwitch]isOn]){
          decodeAction = decodeAction | SKTCaptureLocalDecodeActionBeep;
      }
      else{
          decodeAction = decodeAction& ~SKTCaptureLocalDecodeActionBeep;
      }
      [_lastDeviceConnected setDecodeAction:decodeAction completionHandler:^(SKTResult result) {
          NSLog(@"Setting the Decode Action returned: %ld", (long)result);
          if (result == SKTCaptureE_NOERROR){
              _lastDeviceConnected.localDecodeAction = decodeAction;
          }
          else {
              dispatch_async(dispatch_get_main_queue(), ^{
                  [[self beepSwitch]setOn:![[self beepSwitch]isOn]];
              });
          }
      }];
  }

.. note::
  This code update the UI controls directly in the completion handler and that is
  possible only because the code updating the UI is in the block that has been
  dispatched on the main queue: ``dispatch_async(dispatch_get_main_queue(), ^{...});``

The current state of the device decode action is saved by adding a computed property
``localDecodeAction`` in an Category class for ``CaptureHelperDevice``.
Since a Objective-C Category class cannot declare properties, the original
CaptureHelperDevice and CaptureHelper classes both provide a `extensionProperties`
member which is a dictionary that can be used to implement this kind of feature.

So in this particular example our extension class could look like this::


  #import "SktCaptureHelper.h"

  @interface SKTCaptureHelperDevice (Persistence)
  @property (getter=getLocalDecodeAction, setter=setLocalDecodeAction:)SKTCaptureLocalDecodeAction localDecodeAction;

  @end

and its implementation could be something looking like this::

  #import "SKTCaptureHelperDevice+Persistence.h"

  @implementation SKTCaptureHelperDevice(Persistence)

  -(void)setLocalDecodeAction:(SKTCaptureLocalDecodeAction)decodeAction{
      if(self->_extensionProperties == nil) {
          self->_extensionProperties = [NSMutableDictionary new];
      }
      NSNumber *value = [NSNumber numberWithLong:(long)decodeAction];
      [self->_extensionProperties setValue:value forKey:@"decodeAction"];
  }
  -(SKTCaptureLocalDecodeAction)getLocalDecodeAction{
      if(self->_extensionProperties != nil){
          NSNumber* value = [self->_extensionProperties valueForKey:@"decodeAction"];
          if(value != nil){
              return (SKTCaptureLocalDecodeAction)value.longValue;
          }
      }
      return SKTCaptureLocalDecodeActionNone;
  }
  @end


Here the decode action is stored in the `extensionProperties` of the
CaptureHelperDevice class. That's how we can keep the actual value of the decode
action by adding this computed property: `decodeAction`.


Locate the Scanner
^^^^^^^^^^^^^^^^^^
''Locate the Scanner'' might be a nice feature to help the user identify which
scanner is theirs in a situation where more than one scanner is in the area.
This feature could be implemented with a repeated action of sending a Data
Confirmation to the scanner to cause the scanner to beep or flash or vibrate.
Here is code example of a command that would need to be in a timer handler::

  if(_lastDeviceConnected != nil){
      [_lastDeviceConnected
       setDataConfirmationWithLed:SKTCaptureDataConfirmationLedGreen
          withBeep:SKTCaptureDataConfirmationBeepGood
          withRumble:SKTCaptureDataConfirmationRumbleGood
          completionHandler:^(SKTResult result) {
          NSLog(@"setDataConfirmation returns: %ld",(long)result);
      }];
  }

The ``_lastDeviceConnected`` in this code is set to a ``CaptureHelperDevice``
instance in the ``didNotifyArrivalForDevice`` delegate to reference the last
connected device.

.. note::
  Triggering the scanner remotely shows the scanner aiming light which could
  also help to find or identify the connected scanner. This use requires caution
  though because it might scan a barcode.

.. _wrongbarcodeindicationobjclabel:

Wrong Barcode Indication
^^^^^^^^^^^^^^^^^^^^^^^^
Wrong barcode indication can be useful when a user scans a barcode but that
barcode was not expected at that moment in the application or is not the
expected symbology or format. Of course the
application UI could display a user friendly error, but maybe the user
is scanning a bunch of barcodes without looking at the screen. So sending
back to the user an indication that something is wrong after having
scanning a barcode might be useful.

Here is an example of code that can be invoked when such a condition occurs in the
application::

    [device
     setDataConfirmationWithLed:SKTCaptureDataConfirmationLedRed
        withBeep:SKTCaptureDataConfirmationBeepBad
        withRumble:SKTCaptureDataConfirmationRumbleBad
        completionHandler:^(SKTResult result) {
        NSLog(@"setDataConfirmation returns: %ld",(long)result);
    }];

The ``device`` in this code is a ``CaptureHelperDevice`` object instance.

.. _disablingscannertriggerobjclabel:

Disabling the Scanner Trigger Button
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Upon detection of a wrong barcode and requiring the user to acknowledge an
eventual informational message on the host screen, the Scanner Trigger button
can be disabled.
Here is a sample code for disabling the Scanner Trigger button::

  SKTCaptureTrigger trigger = SKTCaptureTriggerDisable;
  [_lastDeviceConnected setTrigger:
                 trigger completionHandler:^(SKTResult result) {
                     NSLog(@"The trigger is %ld with result %ld",(long)trigger,(long)result);
                 }];

And to re-enable the button::

  SKTCaptureTrigger trigger = SKTCaptureTriggerEnable;
  [_lastDeviceConnected setTrigger:
                 trigger completionHandler:^(SKTResult result) {
                     NSLog(@"The trigger is %ld with result %ld",(long)trigger,(long)result);
                 }];

The _lastDeviceConnected in this code is a ``CaptureHelperDevice`` object
instance.

.. note::
  The Scanner can be configured with a Data Confirmation Mode set to either the
  application or to Capture. In both cases, the trigger is disabled until the data
  is confirmed or a timeout has elapsed. Please refer to the Application Level
  :ref:`Data Confirmation from the App<dataconfirmationappobjclabel>`.