How to navigate to a web page from within a flutter app? (OAuth)

Question

I am trying to build a Flutter app that uses OAuth to connect to a user's account on another website. This requires navigating to the site's OAuth page where the user can enter their credentials, and then parsing the code that's sent back to the app when the user returns.

So my questions are:

1. How can I navigate to the OAuth web page?

I have figured out that I can navigate to an internal route like this:

Navigator.of(context).pushNamed('/some_page');

But what if I want to go to an external page like https://coolsite.com/oauth/authorize?

How can I do this (a) by opening the URL in the local web browser, and (b) with an in-app web view?

2. What URL should I redirect the user to after authenticating so that they go back to the app, and how do I parse the response?

It seems there are 2 ways:

(a) Let the user be redirected to a blank page with the authorization code in the URL and title of the page. If this method - how do I parse the page or URL?

(b) Redirect the user to some kind of scheme, like my-dart-app://coolsite-oauth?code=xyz. If this method - how do I register the scheme, and would cool site-OAuth map to a route that I specify when calling new MaterialApp, or somewhere else? And how would I parse the query param?

Answer 1

You can trigger a navigation using the activity service:

import 'package:flutter/services.dart';

void launchUrl(String url) {
  Intent intent = new Intent()
    ..action = 'android.intent.action.VIEW'
    ..url = url;
  activity.startActivity(intent);
}

There isn't currently a way to receive a navigation in Flutter, but that's something we'd like to add. I've created this issue to track this feature request: https://github.com/flutter/flutter/issues/357