Flutter how to execute when clicking back button

You can listen to the pop with WillPopScope (Creates a widget that registers a callback to veto attempts by the user to dismiss the enclosing [ModalRoute]. -> from documentation):

@overrideWidget build(BuildContext context) { return WillPopScope(  onWillPop: () {    print('Backbutton pressed (device or appbar button), do whatever you want.');    //trigger leaving and use own data    Navigator.pop(context, false);    //we need to return a future    return Future.value(false);  },  child: Scaffold(  ...  ), );}

Hopefully I got your question right and that helps :)!

You can override the default back arrow on the AppBarand then specify the value you would like to return to trigger the change of the state when Navigator.pop is called:

Pseudo-Code

so you need to have something like this in your onPressed callback of your navigation button

onPressed: ()async{            var nav = await Navigator.of(context).push(newRoute);            if(nav==true||nav==null){              //change the state            }          },

and in your newRoute you should have something like this

new AppBar(        leading: new IconButton(          icon: new Icon(Icons.arrow_back),          onPressed: (){Navigator.pop(context,true)}        ),

I am checking for both values null or true because the null value is returned when the user hits the BackButton on android screen (the one in the bottom of the screen). I also believe the null will also be returned with the default BackButton in Flutter so you do not actually need to override the leading property, but I have not checked that myself, so it may be worth checking.