setting sharedInstance of audiosessions category options not working - swift

Question

I'm building an App where I want to play music from the local library AND use the AVQueuePlayer, to play a list of tracks, where once in a while there's a break between the track. The music works totally fine, now, Since I want everything to work in the background, my only option when playing the AVQueuePlayer and want a break, is to play a silent AVPlayerItem (an empty audiofile.) I want the Music to play normally when silent AVPlayerItems are playing, I achieved that by setting AVAudioSession category to .playback and with options: .mixWithOthers, and when a regular track (not silent) is played by the AVQueuePlayer, I want the music to be dimmed a little.
I've tried changing the the audio session like this: AVAudioSession.sharedInstance().setCategory(.playback, options: [.mixWithOthers, .duckOthers])
but it doesn't change anything. When I check if it's changed like this: if AVAudioSession.sharedInstance().categoryOptions == .mixWithOthers {
print("Music mixing with silence")
}
the session category options seem to have changed, but it doesn't affect the audio in the end.
#objc func playerDidFinishPlaying() {
print("Player finished!")
guard let queuePlayer = queuePlayer else { return }
if let index = queuePlayer.items().lastIndex(where: { (playerItem) -> Bool in
return playerItem == queuePlayer.currentItem
}) {
if let nextItem = queuePlayer.items()[index + 1].asset as? AVURLAsset {
if nextItem.url.absoluteString != oneSecondSilenceUrl?.absoluteString {
try? AVAudioSession.sharedInstance().setCategory(.playback, options: [.mixWithOthers, .duckOthers])
//When narrator is speaking
} else {
try? AVAudioSession.sharedInstance().setCategory(.playback, options: .mixWithOthers)
AVAudioSession.sharedInstance()
//When there's silence and only music should be playing
}
}
}
if AVAudioSession.sharedInstance().categoryOptions == .mixWithOthers {
print("Music mixing with silence")
}
try? AVAudioSession.sharedInstance().setActive(true)
}
enter code here
This method runs whenever the the AVQueuePlayer has finished playing one of its items. I use it to check and see if the NEXT item is a silent track or not. If its a silent track, I want .mixWithOthers, If its a track that is NOT silent and the track actually plays audio, I want category options: .duckOthers :)
Any help, response or answer is very much appreciated! :)

Answer 1

Switching to main thread seemed to fix the problem. Weird.
DispatchQueue.main.async {
if AVAudioSession.sharedInstance().categoryOptions != .duckOthers {
try? AVAudioSession.sharedInstance().setActive(false)
try? AVAudioSession.sharedInstance().setCategory(.playback, options: [ .duckOthers])
}
}