Flutter prevent close dialog on back pressed

Question

I am using the showDialog function to build a dialog box, but I need to avoid that when the user presses the back button, the dialog box does not close, this is my code:

showDialog(
      barrierDismissible: false,
      context: context,

      builder: (BuildContext context) {
        // return object of type Dialog
        return AlertDialog(
          title: new Text("Hello"),
          content: new SingleChildScrollView(
            child: Container(),
          actions: <Widget>[
            // usually buttons at the bottom of the dialog

            new FlatButton(
              child: new Text("Close"),
              onPressed: () {
              },
            ),
          ],
        );
      },
    );

How can I get it to not close?

Answer 1

You need to enclose your AlertDialon on a WillPopScope like this:

showDialog(
      barrierDismissible: false,
      context: context,

      builder: (BuildContext context) {
        // return object of type Dialog
        return WillPopScope(
            onWillPop: (){},
            child:AlertDialog(
            title: new Text("Hello"),
            content: new SingleChildScrollView(
              child: Container(),),
            actions: <Widget>[
              // usually buttons at the bottom of the dialog
              new FlatButton(
                child: new Text("Close"),
                onPressed: () {
                },
              ),
            ],
          )
        )
      },
    );

The WillPopScope provides you a onWillPop parameter, where you can pass a function of what you want when the child pop. In this case, the parameter receive an empty function so it wont pop.