cannot find usb audio device when voiceprocessingIO is used

i use audiounit voiceprocessingIO to do two-way voice communication, it will be ok when i use build-in audiodevice and wired headphone. but when i use a usb audio device( lightning hub + usb audio device). i use audiosession api:

[[session currentRoute] outputs]

[[session currentRoute] inputs]

[session availableInputs]

[session inputDataSource]

[session inputDataSources]

[session outputDataSource]

[session outputDataSources]

i can only find build in speaker and build in mic, usb audio device is not work.

when i use remoteio instead voiceprocessingio, it will work fine, and i can find usb audio device by audiosession ap


i find this problem when i use ipad6 and ipad pro with lightning port and 3.5mm audio port.

ipad pro3 with usb audio device is ok when i use voiceprocessingio, because ipad pro3 is type-c port without 3.5mm audio port, usb audio device is treat as headphone.


my question is how can i use usb audio device on ipad6 and ipad pro with voiceprocessingio.

is there any notify when i plug usb audio device when voiceprocessingio is used? i do not receive any audiosession notify