Callkit loudspeaker bug / how WhatsApp fixed it?

Question

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

Answer 1

Above answer is correct, "VoiceChat" mode ruin everything.

Swift 4 example for WebRTC. After connection was established call next

let rtcAudioSession = RTCAudioSession.sharedInstance()
rtcAudioSession.lockForConfiguration()
do {
    try rtcAudioSession.setCategory(AVAudioSession.Category.playAndRecord.rawValue, with: 
    AVAudioSession.CategoryOptions.mixWithOthers)
    try rtcAudioSession.setMode(AVAudioSession.Mode.default.rawValue)
    try rtcAudioSession.overrideOutputAudioPort(.none)
    try rtcAudioSession.setActive(true)
} catch let error {
    debugPrint("Couldn't force audio to speaker: \(error)")
}
rtcAudioSession.unlockForConfiguration()

You can use AVAudioSession.sharedInstance() as well instead RTC