Upgrader

A Flutter package for prompting users to upgrade when there is a newer version of the app in the store.

Overview

When a newer app version is available in the app store, a simple alert prompt or card is displayed. With today's modern app stores, there is little need to persuade users to upgrade because most are already using the auto upgrade feature. However, there may be times when an app needs to be updated more quickly than usual, and nagging a user to upgrade will entice the upgrade sooner. Also, with Flutter supporting more than just Android and iOS platforms in the future, it will become more likely that users on other app stores need to be nagged about upgrading.

Platform Support

Platform	Automatically Supported?	Appcast Supported?
ANDROID	✅ Yes	✅ Yes
IOS	✅ Yes	✅ Yes
LINUX	❌ No	✅ Yes
MACOS	❌ No	✅ Yes
WEB	❌ No	✅ Yes
WINDOWS	❌ No	✅ Yes

Widgets

The widgets come in two flavors: alert or card. The UpgradeAlert widget is used to display the popup alert prompt, and the UpgradeCard widget is used to display the inline material design card.

Alert Example

Just wrap your body widget in the UpgradeAlert widget, and it will handle the rest.

import 'package:flutter/material.dart';
import 'package:upgrader/upgrader.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Upgrader Example',
      home: Scaffold(
          appBar: AppBar(title: Text('Upgrader Example')),
          body: UpgradeAlert(
            child: Center(child: Text('Checking...')),
          )),
    );
  }
}

Screenshot of alert

Cupertino Alert Example

You can also display a Cupertino style dialog by using the dialogStyle parameter.

          body: UpgradeAlert(
            upgrader: Upgrader(dialogStyle: UpgradeDialogStyle.cupertino),
            child: Center(child: Text('Checking...')),
          )

Screenshot of Cupertino alert

Card Example

Just return an UpgradeCard widget in your build method and a material design card will be displayed when an update is detected. The widget will have width and height of 0.0 when no update is detected.

return Container(
        margin: EdgeInsets.fromLTRB(12.0, 0.0, 12.0, 0.0),
        child: UpgradeCard());

Screenshot of card

Localization

The text displayed in the upgrader package is localized in many languages, and supports customization.

Release Notes

The release notes are displayed by default when a new version is available. On Android the release notes are taken from the the WHAT'S NEW section on Google Play when available, otherwise the main app description is used. On iOS the release notes are taken from the App Store What's New section. For appcast), the release notes are taken from the description field.

Customization

The Upgrader class can be customized by setting parameters in the constructor.

appcast: Provide an Appcast that can be replaced for mock testing, defaults to null
appcastConfig: the appcast configuration, defaults to null
canDismissDialog: can alert dialog be dismissed on tap outside of the alert dialog, which defaults to false (not used by UpgradeCard)
countryCode: the country code that will override the system locale, which defaults to null
languageCode: the language code that will override the system locale, which defaults to null
client: an HTTP Client that can be replaced for mock testing, defaults to null
debugDisplayAlways: always force the upgrade to be available, defaults to false
debugDisplayOnce: display the upgrade at least once once, defaults to false
debugLogging: display logging statements, which defaults to false
dialogStyle: the upgrade dialog style, either material or cupertino, defaults to material, used only by UpgradeAlert, works on Android and iOS.
durationUntilAlertAgain: duration until alerting user again, which defaults to 3 days
messages: optional localized messages used for display in upgrader
minAppVersion: the minimum app version supported by this app. Earlier versions of this app will be forced to update to the current version. Defaults to null.
onIgnore: called when the ignore button is tapped, defaults to null
onLater: called when the later button is tapped, defaults to null
onUpdate: called when the update button is tapped, defaults to null
platform: The target platform, defaults to defaultTargetPlatform
shouldPopScope: called when the back button is tapped, defaults to null
showIgnore: hide or show Ignore button, which defaults to true
showLater: hide or show Later button, which defaults to true
showReleaseNotes: hide or show release notes, which defaults to true
willDisplayUpgrade: called when upgrader determines that an upgrade may or may not be displayed, defaults to null

Minimum App Version

The upgrader package can enforce a minimum app version simply by adding a version number to the description field in the app stores.

For the Android Play Store, use this format:

[Minimum supported app version: 1.2.3]

For the iOS App Store, use this format:

[:mav: 1.2.3]

Using that text says that the minimum app version is 1.2.3 and that earlier versions of this app will be forced to update to the current version.

After the app containing this text has been submitted for review, approved, and released on the app store, the version number will be visible to the upgrader package. When the minimum app version is updated in the future, all previously installed apps with this package will recognize and honor that value.

This overrides any value supplied in the minAppVersion parameter.

Android

Add this text to the bottom of the full description field in the Google Play Console under the main store listing.

iOS

Add this text to the bottom of the description field in App Store Connect in the description field.

Android Back Button

When using the UpgradeAlert widget, the Android back button will not dismiss the alert dialog by default. To allow the back button to dismiss the dialog, use shouldPopScope and return true like this:

UpgradeAlert(Upgrader(shouldPopScope: () => true));

Country Code

On iOS, when your app is not in the US App Store, which is the default, you must use the countryCode parameter mentioned above. The upgrader package does not know which country app store to use because it is not provided by iOS. It assumes the app is in the US App Store.

On Android, the upgrader package uses the system locale to determine the country code.

Android Language Code

Android description and release notes language, defaults to en.

Limitations

These widgets work on both Android and iOS. When running on Android the Google Play Store will provide the latest app version. When running on iOS the App Store will provide the latest app version. In all cases, the widget will display the prompt at the appropriate times.

On Android, the version number is often not available from the Google Play Store, such as with the Google Maps app. In this case, the version is listed as Varies with device. That is not a valid version for upgrader and cannot be used. The upgrader widget will not be displayed in this case.

There is an appcast that can be used to remotely configure the latest app version. See appcast below for more details.

Appcast

The class Appcast, in this Flutter package, is used by the upgrader widgets to download app details from an appcast, based on the Sparkle framework by Andy Matuschak. You can read the Sparkle documentation here: https://sparkle-project.org/documentation/publishing/.

An appcast is an RSS feed with one channel that has a collection of items that each describe one app version. The appcast will describe each app version and will provide the latest app version to upgrader that indicates when an upgrade should be recommended.

The appcast must be hosted on a server that can be reached by everyone from the app. The appcast XML file can be autogenerated during the release process, or just manually updated after a release is available on the app store.

The Appcast class can be used stand alone or as part of upgrader.

Appcast Example

This is an Appcast example for Android.

@override
Widget build(BuildContext context) {
  // On Android, setup the Appcast.
  // On iOS, the default behavior will be to use the App Store version.
  final appcastURL =
      'https://raw.githubusercontent.com/larryaasen/upgrader/master/test/testappcast.xml';
  final cfg = AppcastConfiguration(url: appcastURL, supportedOS: ['android']);

  return MaterialApp(
    title: 'Upgrader Example',
    home: Scaffold(
        appBar: AppBar(
          title: Text('Upgrader Example'),
        ),
        body: UpgradeAlert(
          Upgrader(appcastConfig: cfg),
          child: Center(child: Text('Checking...')),
        )),
  );
}

Appcast Sample File

<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/sparkle">
    <channel>
        <title>Debt Now App - Appcast</title>
        <item>
            <title>Version 1.15.0</title>
            <description>Minor updates and improvements.</description>
            <pubDate>Sun, 30 Dec 2018 12:00:00 +0000</pubDate>
            <enclosure url="https://play.google.com/store/apps/details?id=com.moonwink.treasury" sparkle:version="1.15.0" sparkle:os="android" />
        </item>
    </channel>
</rss>

Appcast Class

final appcast = Appcast();
final items = await appcast.parseAppcastItemsFromUri('https://raw.githubusercontent.com/larryaasen/upgrader/master/test/testappcast.xml');
final bestItem = appcast.bestItem();

Customizing the strings

The strings displayed in upgrader can be customzied by extending the UpgraderMessages class to provide custom values.

As an example, to replace the Ignore button with a custom value, first create a new class that extends UpgraderMessages, and override the buttonTitleIgnore function. Next, when calling UpgradeAlert (or UpgradeCard), add the parameter messages with an instance of your extended class. Here is an example:

class MyUpgraderMessages extends UpgraderMessages {
  @override
  String get buttonTitleIgnore => 'My Ignore';
}

UpgradeAlert(Upgrader(messages: MyUpgraderMessages()));

Language localization

The strings displayed in upgrader are already localized in 33 languages. New languages will be supported in the future with minor updates.

Languages supported:

English ('en')
Arabic ('ar')
Bengali ('bn')
Chinese ('zh')
Dutch ('nl')
Filipino ('fil')
French ('fr')
German ('de')
Greek ('el')
Haitian Creole ('ht')
Hebrew ('he')
Hindi ('hi')
Hungarian ('hu')
Indonesian ('id')
Italian ('it')
Japanese ('ja')
Kazakh ('kk')
Khmer ('km')
Korean ('ko')
Lithuanian ('lt')
Mongolian ('mn')
Norwegian ('nb')
Persian ('fa')
Polish ('pl')
Portuguese ('pt')
Russian ('ru')
Spanish ('es')
Swedish ('sv')
Tamil ('ta')
Telugu ('te')
Turkish ('tr')
Ukrainian ('uk')
Vietnamese ('vi')

The upgrader package can be supplied with additional languages in your code by extending the UpgraderMessages class to provide custom values.

As an example, to add the Spanish (es) language (which is already provided), first create a new class that extends UpgraderMessages, and override the message function. Next, add a string for each of the messages. Finally, when calling UpgradeAlert (or UpgradeCard), add the parameter messages with an instance of your extended class. Here is an example:

class MySpanishMessages extends UpgraderMessages {
  /// Override the message function to provide custom language localization.
  @override
  String message(UpgraderMessage messageKey) {
    if (languageCode == 'es') {
      switch (messageKey) {
        case UpgraderMessage.body:
          return 'es A new version of {{appName}} is available!';
        case UpgraderMessage.buttonTitleIgnore:
          return 'es Ignore';
        case UpgraderMessage.buttonTitleLater:
          return 'es Later';
        case UpgraderMessage.buttonTitleUpdate:
          return 'es Update Now';
        case UpgraderMessage.prompt:
          return 'es Want to update?';
        case UpgraderMessage.releaseNotes:
          return 'es Release Notes';
        case UpgraderMessage.title:
          return 'es Update App?';
      }
    }
    // Messages that are not provided above can still use the default values.
    return super.message(messageKey);
  }
}

UpgradeAlert(Upgrader(messages: MySpanishMessages()));

You can even force the upgrader package to use a specific language, instead of the system language on the device. Just pass the language code to an instance of UpgraderMessages when displaying the alert or card. Here is an example:

UpgradeAlert(Upgrader(messages: UpgraderMessages(code: 'es')));

Semantic Versioning

The upgrader package uses the version package that is in compliance with the Semantic Versioning spec at http://semver.org/.

iTunes Search API

There is a class in this Flutter package used by the upgrader widgets to download app details from the iTunes Search API. The class ITunesSearchAPI can be used standalone to query iTunes for app details.

ITunesSearchAPI Example

final iTunes = ITunesSearchAPI();
final resultsFuture = iTunes.lookupByBundleId('com.google.Maps');
resultsFuture.then((results) {
    print('results: $results');
});

Results

Command Line App - Android

There is a command line app used to display the results from Google Play Store. The code is located in bin/playstore_lookup.dart, and can be run from the command line like this:

$ cd bin
$ dart playstore_lookup.dart id=com.google.android.apps.mapslite

Results:

playstore_lookup releaseNotes: • Support plus.codes URLs• Bug fixes
playstore_lookup version: 152.0.0
...

Command Line App - iOS

There is a command line app used to display the results from iTunes Search. The code is located in bin/itunes_lookup.dart, and can be run from the command line like this:

$ dart itunes_lookup.dart bundleid=com.google.Maps