I have an app with Callkit functionality. When I press the loudspeaker button, it will flash and animate to the OFF state (sometimes the speaker is set to LOUD but the icon is still OFF). When I tap on it multiple times... it can be clearly seen that this functionality is not behaving correctly.
However, WhatsApp has at the beginning the loudspeaker turned OFF and after 3+ seconds it activates it and its working. Has anyone encountered anything similar and can give me a solution?
There is a workaround proposed by an apple engineer which should fix callkit not activating the audio session correctly:
a workaround would be to configure your app's audio session (call
configureAudioSession()) earlier in your app's lifecycle, before the-provider:performAnswerCallAction:method is invoked. For instance, you could callconfigureAudioSession()immediately before calling-[CXProvider reportNewIncomingCallWithUUID:update:completion:]in order to ensure that the audio session is fully configured prior to informing CallKit about the incoming call.
From: https://forums.developer.apple.com/thread/64544#189703
If this doesn't help, you probably should post an example project which reproduces your behaviour for us to be able to analyse it further.
Referd from Abnormal behavior of speaker button on system provided call screen
The same issue has been experienced in the previous versions as well. So this is not the new issue happening on the call kit. This issue has to be resolved from iOS. We don't have any control over this.
Please go through the apple developer forum
and
Maybe you can setMode to AVAudioSessionModeDefault.
When I use CallKit + WebRTC
I configure AVAudioSessionModeDefault mode.
Alloc CXProvider and reportNewIncomingCallWithUUID
Use WebRTC , after ICEConnected, WebRTC change mode to AVAudioSessionModeVoiceChat, then speaker issue happen.
Later I setMode back to AVAudioSessionModeDefault, the speaker works well.
来源：https://stackoverflow.com/questions/49170274/callkit-loudspeaker-bug-how-whatsapp-fixed-it