Central.swift

func centralManager(central: CBCentralManager,
                    didDiscoverPeripheral peripheral: CBPeripheral,
                    advertisementData: [String : AnyObject],
                    RSSI: NSNumber) {
    guard let packet = advertisementData[CBAdvertisementDataLocalNameKey] as? String else {
        return
    }
    let version = Int(packet[packet.startIndex..<packet.startIndex.advancedBy(2)])
    let channel = Int(packet[packet.startIndex.advancedBy(2)..<packet.startIndex.advancedBy(4)])
    let cardRawValue = Int(packet[packet.startIndex.advancedBy(4)..<packet.startIndex.advancedBy(6)], radix: 16)
    let card = Card(rawValue: cardRawValue)
    let name = packet[packet.startIndex.advancedBy(6)..<packet.endIndex]
}