Flutter - how to get current context?

问题

I am using Firebase cloud messaging for notifications, and i want to show a dialog or snackbar once i receive a notification when i am inside the application, my problem is that i am initializing the firebase configuration at the top of my widget tree (Splash screen once the app is starting)

_fireBaseMessaging.configure(
  onMessage: (Map<String, dynamic> message) async {
    dynamic data = message['data'];
    ................ // Adding a snackbar/alertdialog here doesn't work
  },
);

obviously if i set a dialog or snackbar it won't show since i need the context of my current page, is there any way to get the current context?

I also tried putting it inside the build widget of my splash screen but still the dialog isn't showing once i am on another page.

 @override
  Widget build(BuildContext context) {
    _fireBaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print("onMessage: $message");
        dynamic data = message['data'];
        if (data['id'] == '1') {
          newPro = true;
        } else if (data['id'] == '2') {
          print("THIS WORKS!!!");
          showDialog(
              context: context,
              builder: (context) => AlertDialog(
                    content: ListTile(
                      title: Text("TEST"),
                      subtitle: Text("TEST"),
                    ),
                    actions: <Widget>[
                      FlatButton(
                        child: Text("OK"),
                        onPressed: () => Navigator.pop(context),
                      )
                    ],
                  ));
        }
      },
    );

回答1:

do the initializing inside a build method of your first widget in the tree ! which normally it called an App widget and it is StateLess StateFull widget and inside the build method you have access to the BuildContext

回答2:

The showDialog method returns a Future:

Future<T> showDialog <T>({
@required BuildContext context,
bool barrierDismissible: true
@Deprecated('Instead of using the "child" argument, return the child from a closure ' 'provided to the "builder" argument. This will ensure that the BuildContext ' 'is appropriate for widgets built in the dialog. ' 'This feature was deprecated after v0.2.3.') Widget child,
WidgetBuilder builder,
bool useRootNavigator: true
})

Therefore add the await keyword to wait for the future to complete:

         await showDialog(
              context: context,
              builder: (context) => AlertDialog(
                    content: ListTile(
                      title: Text("TEST"),
                      subtitle: Text("TEST"),
                    ),
                    actions: <Widget>[
                      FlatButton(
                        child: Text("OK"),
                        onPressed: () => Navigator.pop(context),
                      )
                    ],
                  ));

回答3:

I ended up using Overlay support:

https://pub.dev/packages/overlay_support

It is basically called at the very beginning of my tree just like wrapping providers at the main.dart, it worked like a charm, nothing else worked at all! Also here is a tutorial that helped me a lot:

https://medium.com/flutter-community/in-app-notifications-in-flutter-9c1e92ea10b3

来源：https://stackoverflow.com/questions/59594369/flutter-how-to-get-current-context