Flutter onClosing callback for showModalBottomSheet

Question

I have a showModalBottomSheet like the below, which I understand to inherit from BottomSheet (right?)

      showModalBottomSheet<void>(
        context: context,
        builder: (BuildContext context) {
          return Container(
            height: 260.0,
            child: Text('I am text')
          );
        },
      );

What I want to do:

I want to know (listen) when the modal is being closed, and act on it.

I've seen this onClosing callback: https://docs.flutter.io/flutter/material/BottomSheet/onClosing.html

How can I have a listener attached to the showModalBottomSheet, and then act accordingly when it fires?

Answer 1

Perhaps it's not the best solution, but showModalBottomSheet return a "Future" so you can used it.

For example:

void _showModal() {
    Future<void> future = showModalBottomSheet<void>(
      context: context,
      builder: (BuildContext context) {
        return Container(height: 260.0, child: Text('I am text'));
      },
    );
    future.then((void value) => _closeModal(value));
}
void _closeModal(void value) {
    print('modal closed');
}