title: When to use AVAudioSession.setActive?
body: <p>My understanding is that you can only have 1 AVAudioSession (since it is a singleton and therefore you receive always the same instance) in your app.</p>
  
  <p>So, what is the purpose of the <strong>setActive()</strong> function?  Since I can only have one session, I don't see a proper use case for that function.</p>
  
  <p>AVAudioSession documentation: <a href="https://developer.apple.com/documentation/avfoundation/avaudiosession" rel="noreferrer">https://developer.apple.com/documentation/avfoundation/avaudiosession</a></p>