Get MAC address of bluetooth low energy peripheral in iOS

Question

I am currently working on an iOS application based on bluetooth low energy devices. In order to get a unique identifier to compare the peripherals got, I have to get the MAC

Answer 1

Low energy peripherals may use privacy feature which hides the MAC address, so it is not necessarily even possible to get the address before connection or bonding. If you somehow get the MAC address which goes over the air, you need to handle privacy or you have interoperability problems.

Apple uses UUIDs to abstract these privacy features out so users do not need to worry about those.

Correct way to do that like you wrote is to either add some vendor specific data to advertisement packet or use the Device Information service.

Answer 2

CBPeripheral's identifier property will serve your purpose, available from a still-unconnected device in CBCentralManager's didDiscoverPeripheral delegate method:

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI

CBPeripheral *peripheral ...

NSUUID* serverId = [peripheral identifier];

I have a half dozen LE devices I'm experimenting with, including multiple sets of identical devices. I just confirmed that across two iOS devices, the identifiers for all of these LE widgets were different, but for EACH iOS device, the identifier for each widget was retained across application launches and even across app deletes and reinstalls. I would say this definitively proves that the OS is storing enough info internally that for a given iThing, you'll be able to distinguish between, and re-identify, all the peripherals your app encounters, without actually connecting to them. Also note that the advertisementData, also available before connecting, is full of useful info like CBAdvertisementDataLocalNameKey, CBAdvertisementDataManufacturerDataKey, CBAdvertisementDataServiceUUIDsKey, CBAdvertisementDataSolicitedServiceUUIDsKey, and others, although none as certain to uniquely identify the device as [peripheral identifier] is.

I didn't try doing a device backup and restore to prove the UUIDs were retained, but I'd wager they are, and if they're not, it's something Apple would consider a bug.

Answer 3

You can access to the MAC ADDRESS without problem in iOS 12. To get the mac address you have to follow the next steps.

1. Parse the Data received by the BLE device to String.

extension Data{
func hexEncodedString() -> String {
        let hexDigits = Array("0123456789abcdef".utf16)
        var hexChars = [UTF16.CodeUnit]()
        hexChars.reserveCapacity(count * 2)

        for byte in self {
            let (index1, index2) = Int(byte).quotientAndRemainder(dividingBy: 16)
            hexChars.insert(hexDigits[index2], at: 0)
            hexChars.insert(hexDigits[index1], at: 0)
        }
        return String(utf16CodeUnits: hexChars, count: hexChars.count)
    }
}

2. Add a separator ":" to the address.

extension String {
    func separate(every stride: Int = 4, with separator: Character = " ") -> String {
        return String(enumerated().map { $0 > 0 && $0 % stride == 0 ? [separator, $1] : [$1]}.joined())
    }
}

3. In didReadValueForCharacteristic( characteristic: CBCharacteritic) you can use the previous 2 functions to get the mac address.

func didReadValueForCharacteristic(_ characteristic: CBCharacteristic) {
if characteristic.uuid == BleDeviceProfile.MAC_ADDRESS, let mac_address = characteristic.value?.hexEncodedString().uppercased(){
            let macAddress = mac_address.separate(every: 2, with: ":")
            print("MAC_ADDRESS: \(macAddress)")
        }
}

4. enjoy your mac address: "MAC_ADDRESS: 00:0A:57:4E:86:F2"

Answer 4

On-behalf of the discussion of the other professionals I've found some facts which says -

“iOS hides the MAC address of the device and generates a UUID. The UUID on iOS is generated by the iOS device. Different iOS devices will get different UUIDs for the same peripheral. The MAC address is usually based on the hardware. If we both have iPhones and scan the same peripheral, we'll see different UUIDs. iOS generates the UUID on the device and hides the MAC address.

Summary - iOS doesn't let you get the MAC address of a device, it gives you a random UUID instead.“


Source - https://github.com/don/cordova-plugin-ble-central/issues/77

As per above study I've found that there’s not such a unique way to get connect to the board so far, Every board has a MAC address, which Doesn’t changes and easy to access in (only) Android, while iOS doesn’t allow to access MAC Address of the peripheral, however iOS use this MAC address to create a peripheral identifier (UUID), which is unique on (unique) device only. The peripheral identifier for a single Board is different for different iPhones devices (but unique on single device).

However we can connect to a board by searching with Peripheral's Bluetooth Service UUID, but this service UUID is same for all the boards of a kind say- “Adafruit Feather M0”. It means the App will look around the BLE boards of the same type (“Adafruit Feather M0”) and will get connect to ANY one of them. In order to connect to a particular user to a specific Board doesn’t seems to be possible so far due to the inaccessibility of MAC and giving the random UUID in iOS.

Answer 5

Updated Answer :-

After iOS 12 we can get UDID

   print(UIDevice.current.identifierForVendor)

   print(UIDevice.current.identifierForVendor?.uuidString)

Before iOS 12**

There is no public API to get this information.

If this is an internal or jailbreak application you can get the value of the kLockdownBluetoothAddressKey key via liblockdown.dylib