Playing one sound instance at a time - swift

Question

I have an application that is constantly receiving integer data from a bluetooth sensor and I made it so that if the integer is less than 50, then it should play the MP3.
The problem is that the sensor is very rapidly checking and sending the integers, which is resulting in too many audio instances, basically the the mp3 file is being played too many times at the same time. How can I have it so that it finishes the audio before starting again?
This is the main code:
var player: AVAudioPlayer?
if let unwrappedString = Reading {
let optionalInt = Int(unwrappedString)
if let upwrappedInt = optionalInt {
if(upwrappedInt < 50){
DispatchQueue.global(qos: .background).async {
self.playSound()
}
}
}
}
Sound function:
func playSound() {
guard let url = Bundle.main.url(forResource: "beep1", withExtension: "mp3") else {
print("url not found")
return
}
do {
/// this codes for making this app ready to takeover the device audio
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try AVAudioSession.sharedInstance().setActive(true)
/// change fileTypeHint according to the type of your audio file (you can omit this)
player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileTypeMPEGLayer3)
// no need for prepareToPlay because prepareToPlay is happen automatically when calling play()
player!.play()
} catch let error as NSError {
print("error: \(error.localizedDescription)")
}
}

Answer 1

If the audio player is already playing (isPlaying), don't start playing!
https://developer.apple.com/reference/avfoundation/avaudioplayer/1390139-isplaying

Answer 2

I believe AVAudioPlayer has a delegate method to check if the audio has finished playing:
-(void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
// ----------------------------------------------
// set your custom boolean flag 'isPlayingAudio'
// to false so you can play another audio again
// ----------------------------------------------
}
...
-(void)monitorBluetoothNumber
{
if(bluetoothNumber < 50 && !self.isPlayingAudio)
{
[self playMusic];
self.isPlayingAudio = YES;
}
}
You'll need to setup your audio player and set its delegate obviously.
The code is Objective C but you can easily adapt to Swift.