duckOthers Audio Session Interrupted by Remote Push Notification - ios

Question

I have a workout app that plays short clips of sound every couple of seconds. I have background music enabled so that music from other apps can be played while working out. The problem arises when I get a remote push notification (in my case, Slack) that has a sound, which somehow cancels out my duckingOther audio session and the music from other apps becomes loud again.
Question - How do I reset my duckingOthers audiosession when the user gets this type of interruption?
I set the audio session by calling the below function in didFinishLaunchingWithOptions:
private func setupAudioSession(){
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, with: [.mixWithOthers, .duckOthers, .interruptSpokenAudioAndMixWithOthers])
print("AVAudioSession Category Playback OK")
do {
try AVAudioSession.sharedInstance().setActive(true)
print("AVAudioSession is Active")
} catch let error as NSError {
print(error.localizedDescription)
}
} catch let error as NSError {
print(error.localizedDescription)
}
}
I have tried treating this as a hard interruption (for example a phone call), but when trying to apply the techniques used for this type of interruption, it seems that remote push notifications pass through the cracks. Below is what I used from a different question to try and catch interruptions.
#objc func handleInterruption(notification: Notification) {
guard let userInfo = notification.userInfo,
let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
let type = AVAudioSessionInterruptionType(rawValue: typeValue) else {
return
}
if type == .began {
// Interruption began, take appropriate actions
print("interruption started")
}
else if type == .ended {
if let optionsValue = userInfo[AVAudioSessionInterruptionOptionKey] as? UInt {
let options = AVAudioSessionInterruptionOptions(rawValue: optionsValue)
if options.contains(.shouldResume) {
// Interruption Ended - playback should resume
print("should resume playback")
setupAudioSession()
} else {
// Interruption Ended - playback should NOT resume
print("should not resume playback")
}
}
}
}
func setupNotifications() {
let notificationCenter = NotificationCenter.default
notificationCenter.addObserver(self,
selector: #selector(handleInterruption),
name: .AVAudioSessionInterruption,
object: nil)
}