title: Is this a bug of iOS background location updates?
body: <p>I have created an app which uses location updates in the background.When it goes to background ,then i start one background Task that is timer to call startUpdatingLocation for every 30 seconds,another timer to call stopUpdatingLocation after startUpdatingLocation.I write a LogTool to record app info when it is in background.I know the app.backgroundTimeRemaining is the same no matter the app is in background or foreground when CLLocationManager startUpdatingLocation(Am i right ?),but it will be reseted to 180s When CLLocationManager stopUpdatingLocation.I used iPhone5s ,iOS 8.3.</p>
  <pre><code>-(void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
  WWLOG(@&quot;locationManager didUpdateLocations&quot;);
  [LogTool writeContentToFile:@&quot;locationManager didUpdateLocations&quot;];
  UIApplication *app = [UIApplication sharedApplication];
  [LogTool writeContentToFile:[NSString stringWithFormat:@&quot;backGroundRemainingTime:(%f)&quot;,app.backgroundTimeRemaining]];
  </code></pre>
  <p>}</p>
  <p>The app goes well for hours in background,but suddenly the app.backgroundTimeRemaining change to about 160s.Is this a bug ?
  Here is a part of record.</p>
  <blockquote>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 00:00:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 00:00:05 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  </blockquote>
  <p><em><strong>It goes well,then...</strong></em></p>
  <blockquote>
  <p>2015-12-10 04:44:39 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:44:39 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)</p>
  <p>2015-12-10 04:44:40 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:44:40 backGroundRemainingTime:(179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000)
  2015-12-10 04:44:41 time:2015-12-10 04:44:36 sessionId:3C95D7CC-E9D3-4B58-BCC2-384CB3EE5A47 lat:22548016l lon:113955506l accuracy:5000l</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.940208)</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.771241)</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.730064)</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.702347)</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.678130)</p>
  <p>2015-12-10 04:45:01 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:01 backGroundRemainingTime:(160.546829)</p>
  <p>2015-12-10 04:45:05 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:05 backGroundRemainingTime:(157.161099)</p>
  <p>2015-12-10 04:45:06 locationManager didUpdateLocations</p>
  <p>2015-12-10 04:45:06 backGroundRemainingTime:(156.088492)</p>
  </blockquote>