title: How long time usually application is given to finish in background (backgroundTimeRemaining)
body: <p>I need to get user location update when application is in background. I used "significant change feature" but the problem with significant change it's not accurate.</p>
  
  <p>Hence, to  improve accuracy of  "significant change" a "little bit" I'm thinking to complement this with <code>UIApplication:beginBackgroundTaskWithExpirationHandler:</code>.</p>
  
  <p>Thus, my question is how long usually application is given (the value in <code>backgroundTimeRemaining</code>) to run in background.</p>