How can I allow background music to continue playing while my app still plays its sounds while using Swift

Question

I created an app and I am attempting to allow the user to continue to listen to their music while playing my game, but whenever they hit \"play\" and the ingame sounds occur

Answer 1

If you want to play an alert sound:

public func playSound(withFileName fileName: String) {

    if let soundUrl = Bundle.main.url(forResource: fileName, withExtension: "wav") {
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryAmbient, with:[.duckOthers])
            try AVAudioSession.sharedInstance().setActive(true)

            var soundId: SystemSoundID = 0

            AudioServicesCreateSystemSoundID(soundUrl as CFURL, &soundId)
            AudioServicesAddSystemSoundCompletion(soundId, nil, nil, { (soundId, clientData) -> Void in
                AudioServicesDisposeSystemSoundID(soundId)
                do {
                    // This is to unduck others, make other playing sounds go back up in volume
                    try AVAudioSession.sharedInstance().setActive(false)
                } catch {
                    DDLogWarn("Failed to set AVAudioSession to inactive. error=\(error)")
                }
            }, nil)

            AudioServicesPlaySystemSound(soundId)
        } catch {
            DDLogWarn("Failed to create audio player. soundUrl=\(soundUrl) error=\(error)")
        }
    } else {
        DDLogWarn("Sound file not found in app bundle. fileName=\(fileName)")
    }
}

And if you want to play music:

import AVFoundation

var audioPlayer:AVAudioPlayer?

public func playSound(withFileName fileName: String) {

    if let soundUrl = Bundle.main.url(forResource: fileName, withExtension: "wav") {
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryAmbient, with:[.duckOthers])
            try AVAudioSession.sharedInstance().setActive(true)

            let player = try AVAudioPlayer(contentsOf: soundUrl)
            player.delegate = self
            player.prepareToPlay()
            DDLogInfo("Playing sound. soundUrl=\(soundUrl)")
            player.play()
            // ensure the player does not get deleted while playing the sound
            self.audioPlayer = player
        } catch {
            DDLogWarn("Failed to create audio player. soundUrl=\(soundUrl) error=\(error)")
        }
    } else {
        DDLogWarn("Sound file not found in app bundle. fileName=\(fileName)")
    }
}

func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
    self.audioPlayer?.stop()
    do {
        // This is to unduck others, make other playing sounds go back up in volume
        try AVAudioSession.sharedInstance().setActive(false)
    } catch {
        DDLogWarn("Failed to set AVAudioSession inactive. error=\(error)")
    }
}