// When the app goes into the background the DidEnterBackground() function is called and it looks like this:
public override void WillEnterForeground(UIKit.UIApplication application)
{
    SAMISMPManager.SharedManager.BarcodeReader.PowerOn();
    SAMISMPManager.SharedManager.BarcodeReader.EnableTrigger(true);
    SAMISMPManager.SharedManager.BarcodeReader.EnableSymbology(eICBarCodeSymbologies.ICBarCode_QRCode, true);
    IBarcodeScanner.BarcodeScanned -= IBarcodeScanner_BarcodeScanned;

// When the app goes into the foreground the WillEnterForeground() function is called and it looks like this:
public override void DidEnterBackground(UIApplication application)
{
    ExternalAccessoryManagement.sharedManager = SAMISMPManager.SharedManager;
    ExternalAccessoryManagement.sharedManager.Delegate = new MySamIsmpDelegate(this.ConnectionStatusChange);
    ExternalAccessoryManagement.sharedChannel = ICAdministration.SharedChannel as ICAdministration;
    ExternalAccessoryManagement.sharedChannel.Open();

    EFT.sharedChannel = ICAdministration.SharedChannel as ICAdministration;
    EFT.sharedChannel.Delegate = new MyICAdministrationStandAloneDelegate();

    NSMutableData transaction = new NSMutableData();
    var header = new byte[]{
        0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00,
        };
    transaction.AppendBytes(header);
    var getLastTransactionCommand = BitConverter.GetBytes(2060);

    if (BitConverter.IsLittleEndian)
    Array.Reverse(getLastTransactionCommand); //reverse it so we get big endian.
    transaction.AppendBytes(getLastTransactionCommand);
    var dataLength = new byte[]{
        0x00, 0x00, 0x00, 0x00,
    };
    transaction.AppendBytes(dataLength);
     bool result = sharedChannel.SendMessage(transaction);

    this.IEFT.OpenConnection();
    this.IBarcodeScanner = new BarcodeScanner(this.IEAManagement);
    this.IBarcodeScanner.OpenScannerConnection();
    IBarcodeScanner.BarcodeScanned += IBarcodeScanner_BarcodeScanned;
}