CallKit Audio session starts when navigating to the application only - ios

Question

I'm working on a voip app now and want to support holding.
But when a second call comes and I hold my current call. Switching to my first call I hear no sound at all.
The way to hear it is to navigate from callKit native screen to my app and hence I can hear the voice.
func configureAudioSession() {
_ = try? AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playAndRecord, mode: .videoChat, options: AVAudioSession.CategoryOptions.mixWithOthers)
_ = try? AVAudioSession.sharedInstance().overrideOutputAudioPort(AVAudioSession.PortOverride.none)
_ = try? AVAudioSession.sharedInstance().setMode(AVAudioSession.Mode.voiceChat)
}
func startAudio() {
print("Starting audio")
do {
_ = try AVAudioSession.sharedInstance().setActive(true)
} catch {
}
}
func stopAudio() {
print("Stopping audio")
do {
_ = try AVAudioSession.sharedInstance().setActive(false)
} catch {
}
}

Answer 1

For supporting holding, you dont have to start/stop audio session, instead you can use CXSetHeldCallAction provided by Callkit itself. Here, is the code for hold that i use.
let callKitCallController = CXCallController()
func performHoldAction(isOnHold:Bool, uuid:UUID) {
let holdCallAction = CXSetHeldCallAction(call: uuid, onHold: isOnHold)
let transaction = CXTransaction(action: holdCallAction)
callKitCallController.request(transaction) { error in
if let error = error {
CPrint("holdCallAction transaction request failed: \(error.localizedDescription).")
return
}
CPrint("holdCallAction transaction request successful")
}
}
Once system puts the call on hold(by above method OR due to other incoming call accepting or any other reason), then in CXProviderDelegate, the method func provider(_ provider: CXProvider, perform action: CXSetHeldCallAction) gives you the callback for the detail.
Here, system/callkit itself interacts with audio, you dont have to explicitly start or stop audio for holding.
Note: Make sure that you given supportsHolding to true for the CXCallUpdate that you gave for new call.