Flutter snackbar dismiss on SnackBarAction onPressed

Try using hideCurrentSnackBar method

onPressed: () {
    homeScaffoldKey.currentState.hideCurrentSnackBar();
},

More info here: https://docs.flutter.io/flutter/material/ScaffoldState/hideCurrentSnackBar.html

You can also use,

Scaffold.of(context).hideCurrentSnackBar();

Be careful when you use context, use the correct context.

NOTE

In the new Flutter Version, this method is deprecated. Therefore use

ScaffoldMessenger.of(context).hideCurrentSnackBar();