Writing an SDK With Core Bluetooth – 18 – The Answer

At this point, the Peripheral is getting the question. Time to answer it.

The user of the Peripheral Mode device now has a question that was asked by the Central Mode device displayed. They select an answer, or simply hit the “SEND A RANDOM ANSWER” button. This will initiate the process illustrated in the timeline above.

Here’s what is happening:

1. The app uses the SDK’s “sendAnswer(_:)” method of the ITCB_SDK_Device_Central instance that was sent with the question, to send the answer (as a String).
2. The ITCB_SDK_Device_Central instance calls the Core Bluetooth CBPeripheralManager.updateValue(-:, for:, onSubscribedCentrals:) method to send the new value of the answer Characteristic to the Central.
3. The Peripheral gets a confirmation callback, using the observer answerSentToDevice(_:, answer:, toQuestion:) method, that the answer was sent.
4. On the Central end of things, the CBPeripheral that was associated with the Peripheral device is notified that a Characteristic value has a proposed update, and uses the CBPeripheralDelegate.peripheral(_:, didUpdateValueFor:, error:) method of the ITCB_SDK_Device_Peripheral instance that the Central had assigned to the Peripheral.
5. The device instance will then use the ITCB_SDK_Central instance to send the questionAnsweredByDevice(_:)observer callback to the app.

In the next entry, we’ll walk through the code that implements this.