How to play sounds, like the ringing beep, while using Callkit?

Question

I am trying to implement VoIP using webRTC and Callkit. The audio works perfectly fine during the call, but I would like to play sounds to the user while the user is initiating a call (an outgoing call).

When the user initiates a call and waits for the recipient to answer, i would like to play the waiting beep sound (long beeps). I can manage to play the sound without using Callkit but when I inform Callkit about an outgoing call it somehow cancels the audio. My assumption is it does this because it IOS silences audio when a call is beging made.

So my question is, how can i playback an mp3 file when Callkit is active. Or is this waiting sound somehow integrated in Callkit or WebRTC?

I messed around with different categories for the audiosession but no luck so far. See below a summary of my current code.

public var audioPlayer: AVAudioPlayer?

private init() {
    do {
        audioPlayer = try AVAudioPlayer(contentsOf: URL(fileURLWithPath: Bundle.main.path(forResource: "dialring", ofType: "mp3")!))
        audioPlayer!.prepareToPlay()
        audioPlayer!.numberOfLoops = -1 //loop
    } catch {
        print(error.localizedDescription)
    }
}

func provider(_ provider: CXProvider, perform action: CXStartCallAction) {
    configureAudioSession()
    audioPlayer?.play()
}

func configureAudioSession() {
    print("Configuring audio session")
    let session = AVAudioSession.sharedInstance()
    do {
        try AVAudioSession.sharedInstance().setCategory(.playAndRecord, options: [.mixWithOthers])
        try session.setMode(AVAudioSession.Mode.voiceChat)
    } catch (let error) {
        print("Error while configuring audio session: \(error)")
    }
}

If anyone could point me in the right direction I would be grateful.

EDIT: I have background mode for audio enabled.

Answer 1

Threw around the structure a bit and now it works. I am not exactly sure what changed thought. If people face the same issue. - Make sure you keep a strong reference to the audioplayer. - Make sure the mode is either in .playback or .playAndRecord