Hi there!
I'm developing a dual-mode bluetooth accessory and would like to pair it through AccessorySetupKit. I'm using an ESP32 with Bluekitchen btstack. This supports CTKD, which seems to be a requirement for the Bluetooth transport bridging according the WWDC19 session 901. I've been in contact with the btstack developer and verified that I can get the device to generate an LTK for the classic transport when reading an encrypted attribute. I'm not able to get this to work with the bluetoothTransportBriding option with AccessorySetupKit though.
What I've found so far is that if I omit the .bluetoothTransportBriding option during pairing I will get a pairing request when I read an encrypted attribute after connecting with the CBConnectPeripheralOptionEnableTransportBridgingKey option. If I accept this request it seems like the system automatically brings up the A2DP profile.
However if I include .bluetoothTransportBriding and/or .bluetoothPairingLE this option does not pop up, but the system does not bring up the A2DP profile. In this case things seem to end up in a weird situation where the device doesn't show up for pairing in Bluetooth Settings either, making it impossible to manually connect for A2DP.
Based on the AccessorySetupKit example from WWDC24 I've created a dice accessory firmware for ESP32 using btstack. The code for this is available here: https://github.com/ljodal/esp32-btstack-ctkd-test
I've also tweaked the AccessorySetupKit example app for iOS to add the ASAccessory.SupportOptions. The code for that is available here: https://github.com/ljodal/accessorysetupkit-ctkd-test
Is there any documentation available anywhere on what is expected of the device for Bluetooth Transport Bridging to work with AccessorySetupKit?