Swift 3 - CBPeripheral.services nil problem

RE: Swift 3 - CBPeripheral.services nil problem

Mostafa Berg — Mon, 20 Feb 2017 08:08:30 GMT

No, those are the characteristics, you should scan only for the service first, using that UUID:

`6E400001-B5A3-F393-E0A9-E50E24DCCA9E` //UART Service

After that service is discovered, you should discover characteristics for this service, you may use a nil filter to discover all, or specify only the RX/TX characteristic UUIDs like so:

`6E400002-B5A3-F393-E0A9-E50E24DCCA9E` //RX Characteristic
`6E400003-B5A3-F393-E0A9-E50E24DCCA9E` //TX Characteristic

after those are discovered, you may proceed to write/read form those characteristics.

RE: Swift 3 - CBPeripheral.services nil problem

MANGO — Sun, 19 Feb 2017 14:00:25 GMT

Hi, Mostafa. Thanks for your guidance.

You should specify the services you're interested in discovering

Does this mean I have to specify the UUID of NUS TX and RX, which are

6e400002-b5a3-f393-e0a9-e50e24dcca9e // RX UUID
6e400003-b5a3-f393-e0a9-e50e24dcca9e // TX UUID

RE: Swift 3 - CBPeripheral.services nil problem

Mostafa Berg — Mon, 06 Feb 2017 13:24:47 GMT

You are on the right track, but you are still missing the service and characteristic discovery steps.

When you connect to a peripheral, you should call discoverServices, and when you get the callback to didDiscoverServices, the services property of your CBPeripheral will be populated.

Afterwards, you should discover characteristics for each service using the discoverCharacteristics method, you will then get a callback to didDiscoverCharacteristics, at this point, your CBPeriphreal will include all the Services/Characteristics. without those steps, it'll all remain Nil.

Tips: You should specify the services you're interested in discovering, leaving this filter Nil will work, but is discouraged by Apple.

And here is the code that can walk you through how the nRFToolbox app does it

RE: Swift 3 - CBPeripheral.services nil problem

MANGO — Mon, 06 Feb 2017 12:20:35 GMT

Hi, Bjørn.

It seems that the centralManagerDidSelectPeripheral calls connectPeripheral in NORBluetoothManager.swift while connecting with the peripheral.

Where can I find the code about UART service discovery and read/write?

RE: Swift 3 - CBPeripheral.services nil problem

bjorn-spockeli — Mon, 06 Feb 2017 09:46:21 GMT

I recommend that you take a look at the nRF Toolbox app source code, found here on our GitHub page. You can find the code for the UART module here.

Best regards

Bjørn