How to use back option in flutter programmatically - flutter

Question

I am calling a method and trying to go back after the transections is done. But the code doesn't work. Here is what I am trying,
onPressed: (){
_updateResult(context);
},
void _updateResult(BuildContext context) async{
// some api calls and checks goes here
Navigator.of(context).pop();
}
This is how I visit to a page
Navigator.push(context, SlideLeftRoute(page: EnterResult(item)));
I have a custom class SlideLeftRoute
class SlideLeftRoute extends PageRouteBuilder {
final Widget page;
SlideLeftRoute({this.page})
: super(
pageBuilder: (
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
) =>
page,
transitionsBuilder: (
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
Widget child,
) =>
SlideTransition(
position: Tween<Offset>(
begin: const Offset(1, 0),
end: Offset.zero,
).animate(animation),
child: child,
),
);
}
THE PROBLEM CODE
I have found which code creates problems. Here I was calling another method for showing dialogue. if I comment the code it works
void _showMsg(msg) {
// flutter defined function
showDialog(
context: context,
builder: (BuildContext context) {
// return object of type Dialog
return AlertDialog(
backgroundColor: Colors.grey[800],
content: new Text(msg,
style: TextStyle(
color: Colors.white,
fontSize: 14.0,
decoration: TextDecoration.none,
fontFamily: 'Lato',
fontWeight: FontWeight.normal,
),
),
//content: new Text("Alert Dialog body"),
actions: <Widget>[
// usually buttons at the bottom of the dialog
new FlatButton(
child: new Text("Close"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
So here after the api call is done, it should go to the back screen but nothing happening.
Thank you.

Answer 1

The problem is because when you call Navigator.of(context).pop(); from the action of an alert AlertDialog, it will pop the presented dialog. You have to pop your screen again. For that you can use future returning by showDialog method.
That is change your _showMsg method like following.
Note the then(..)... on showDialog
void _showMsg(msg) async {
// flutter defined function
await showDialog(
context: context,
builder: (BuildContext localContext) {
// return object of type Dialog
return AlertDialog(
backgroundColor: Colors.grey[800],
content: new Text(
msg,
style: TextStyle(
color: Colors.white,
fontSize: 14.0,
decoration: TextDecoration.none,
fontFamily: 'Lato',
fontWeight: FontWeight.normal,
),
),
//content: new Text("Alert Dialog body"),
actions: <Widget>[
// usually buttons at the bottom of the dialog
new FlatButton(
child: new Text("Close"),
onPressed: () async {
print("poping");
Navigator.of(context).pop();
},
),
],
);
},
).then((value) {
print("poping from screen");
Navigator.of(context).pop();
});
}