onClose method

@override void onClose()

Called before onDelete method. onClose might be used to dispose resources used by the controller. Like closing events, or streams before the controller is destroyed. Or dispose objects that can potentially create some memory leaks, like TextEditingControllers, AnimationControllers. Might be useful as well to persist some data on disk.

Implementation

@override
void onClose() {
  assert(() {
    if (_tickers != null) {
      for (final ticker in _tickers!) {
        if (ticker.isActive) {
          throw FlutterError.fromParts(<DiagnosticsNode>[
            ErrorSummary('$this was disposed with an active Ticker.'),
            ErrorDescription(
              '$runtimeType created a Ticker via its GetTickerProviderStateMixin, but at the time '
              'dispose() was called on the mixin, that Ticker was still active. All Tickers must '
              'be disposed before calling super.dispose().',
            ),
            ErrorHint(
              'Tickers used by AnimationControllers '
              'should be disposed by calling dispose() on the AnimationController itself. '
              'Otherwise, the ticker will leak.',
            ),
            ticker.describeForError('The offending ticker was'),
          ]);
        }
      }
    }
    return true;
  }());
  super.onClose();
}