January 11, 2019

766 words 4 mins read



The Google I/O 2019 Android App

repo name google/iosched
repo link https://github.com/google/iosched
homepage https://play.google.com/store/apps/details?id=com.google.samples.apps.iosched
language Kotlin
size (curr.) 54604 kB
stars (curr.) 19621
created 2014-04-01
license Other

Google I/O Android App

Build Status

Google I/O is a developer conference held each year with three days of deep technical content featuring technical sessions and hundreds of demonstrations from developers showcasing their technologies.

This project is the Android app for the conference.

For a simpler fork of the app, check out the Android Dev Summit App in the adssched branch. In this variant some features are removed, such as reservations and the map screen, and Instant App support is added.


The app displays a list of conference events - sessions, office hours, app reviews, codelabs, etc. - and allows the user to filter these events by event types and by topics (Android, Firebase, etc.). Users can see details about events, and they can star events that interest them. Conference attendees can reserve events to guarantee a seat.

Other features include a Map of the venue, informational pages to guide attendees during the conference in Info, and time-relevant information during the conference in Home.

Development Environment

The app is written entirely in Kotlin and uses the Gradle build system.

To build the app, use the gradlew build command or use “Import Project” in Android Studio. A canary or stable version >= 3.4 of Android Studio is required and may be downloaded here.


The 2019 version of the app is built on top of the last year’s app. The architecture is built around Android Architecture Components.

We followed the recommendations laid out in the Guide to App Architecture when deciding on the architecture for the app. We kept logic away from Activities and Fragments and moved it to ViewModels. We observed data using LiveData and used the Data Binding Library to bind UI components in layouts to the app’s data sources.

We used a Repository layer for handling data operations. IOSched’s data comes from a few different sources - user data is stored in Cloud Firestore (either remotely or in a local cache for offline use), user preferences and settings are stored in SharedPreferences, conference data is stored remotely and is fetched and stored in memory for the app to use, etc. - and the repository modules are responsible for handling all data operations and abstracting the data sources from the rest of the app (we liked using Firestore, but if we wanted to swap it out for a different data source in the future, our architecture allows us to do so in a clean way).

We implemented a lightweight domain layer, which sits between the data layer and the presentation layer, and handles discrete pieces of business logic off the UI thread. See the .\*UseCase.kt files under shared/domain for examples.

We used Navigation component to simplify into a single Activity app.

We used Room for Full Text Search using Fts4 to search for a session, speaker, or codelab.

We used Dagger2 for dependency injection and we heavily relied on dagger-android to abstract away boiler-plate code.

We used Espresso for basic instrumentation tests and JUnit and Mockito for unit testing.


The app makes considerable use of the following Firebase components:

  • Cloud Firestore is our source for all user data (events starred or reserved by a user). Firestore gave us automatic sync and also seamlessly managed offline functionality for us.
  • Firebase Cloud Functions allowed us to run backend code. The reservations feature heavily depended on Cloud Functions working in conjuction with Firestore.
  • Firebase Cloud Messaging let us inform the app about changes to conference data on our server.
  • Remote Config helped us manage in-app constants.


We made an early decision to rewrite the app from scratch to bring it in line with our thinking about modern Android architecture. Using Kotlin for the rewrite was an easy choice: we liked Kotlin’s expressive, concise, and powerful syntax; we found that Kotlin’s support for safety features for nullability and immutability made our code more resilient; and we leveraged the enhanced functionality provided by Android Ktx extensions.


Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at


Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.
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