iOS - SDK - no printer found

Hi I'm new to this whole printing thing.  I have looked through the sdk am stuck with connecting to the printer.

Used the connecting bluetooth sample functions from the iOS documentation, which I translated into swift, but no printer was found.  Tried this with device already connected to iOS and not connected to iOS.

        var serialNumber = ""

        let sam = EAAccessoryManager.shared()

        let connectedAccessories = sam.connectedAccessories as Array<EAAccessory>

        for accessory in connectedAccessories {

            if accessory.protocolStrings.contains("com.zebra.rawport") {

                serialNumber = accessory.serialNumber

                break

            }

        }

        let thePrinterConn : ZebraPrinterConnection = MfiBtPrinterConnection(serialNumber: serialNumber)

        var success = thePrinterConn.open()

        print(success)

Any ideas? What am I missing?