didChangeAppLifecycleState method

@override void didChangeAppLifecycleState(AppLifecycleState state)

Called when the system puts the app in the background or returns the app to the foreground.

An example of implementing this method is provided in the class-level documentation for the WidgetsBindingObserver class.

This method exposes notifications from SystemChannels.lifecycle.

See also:

• AppLifecycleListener, an alternative API for responding to application lifecycle changes.

Implementation

@override
void didChangeAppLifecycleState(AppLifecycleState state) {
  final hub = _hub;
  if (!_isActive || hub == null) return;
  // Reserve event metadata immediately at the start of lifecycle change
  final reservation = hub.reserveEventMetadata();
  final now = DateTime.now();
  final previous = _currentState;
  final sinceLast = _lastStateChange != null
      ? now.difference(_lastStateChange!).inMilliseconds
      : null;
  _currentState = state;
  _lastStateChange = now;
  _isInBackground = _mapIsBackground(state);

  final stage = _mapStage(state);
  hub.captureEvent(
      AppLifecycleEventBase(
        stage: stage,
        viewName: null,
        timeSinceLastChangeMs: sinceLast,
        previousState: previous?.name,
      ),
      reservation);
}