title: Flutter: cross-platform way to keep application running in the background
body: <p>I'm trying to figure out a way to keep a Flutter application running even if it's not in focus. For instance have a countdown running and play an alarm sound/show notification on completion, no matter what's running in foreground.
  Can anyone point me in the right direction? Ideally something that works cross-platform.</p>
  
  <p>I found this <a href="https://stackoverflow.com/questions/41924890/how-do-i-run-code-in-the-background-even-with-the-screen-off/42101998#42101998">thread</a> but it's almost 2 years old, so I'm thinking maybe there has been some development since then.</p>