We're integrating a web based group calling application within a native iOS application and finding that every time a CallKit session gets fully established the web based media streams break, rendering as gray with no audio.
Up to iOS 18 we worked around it by not fulfilling the call start action but that's no longer an option as the audio stopped getting automatically redirected to the speakers. We would now need the CXProvider's didActivateAudioSession callback but that would break the video.
The sample project loads up a simple webpage in a WKWebView which contains a video tag streaming the media from the device's camera.
At the same time it sets up a new CallKit session by requesting and fulfilling a CXStartCallAction transaction.
You will notice that the media doesn't render and, if you are to follow the warnings we left, you will find that not fulfilling the CXStartCallAction fixes it.
Unfortunately that's not a workaround we can use as we need the CXProvider delegate to inform us about audio session changes so we can redirect the audio to the speaker (so the proximity sensor doesn't activate and locking the screen doesn't end the call)
Any insights or workarounds would be greatly appreciated.