AVAudioPlayer start audio playback in the background on a timer?

Question

Swift

1. Enabled Audio, AirPlay and Picture in Picture in BackgroundModes
2. do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try AVAudioSession.sharedInstance().setActive(true)
} catch _ {
return print("error")
}
I set the category AVAudioSessionCategoryPlayback
3. I start the player in a timer
The fact is that every 20 seconds a sound is emitted on the open screen (music plays), but when I simply close the application, it does not work. Who faced, who can help solve the problem?