Chrystian Vieyra Cortes
Director of Engineering
Washington, District of Columbia, United States
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Chrystian Vieyra Cortes is Director of Engineering at Thomson Reuters, where he leads mobile teams building cross-platform news experiences. A longtime Android and iOS developer, Chrystian specializes in sensor data visualization and has published several popular educational apps. Originally from Celaya, Mexico, he came to the United States as a student to earn a B.S. in Computer Science from Western Illinois University and later made the U.S. his permanent home.
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Live Activities and Live Updates on iOS and Android
Users increasingly expect real time status updates without needing to open an app or deal with noisy notifications. Apple addressed this with Live Activities, and Android 16 introduces Live Updates with a similar goal.
In this talk, we compare Live Activities on iOS and Live Updates on Android from a practical, cross platform perspective. We focus on the user experience they enable, how their lifecycles differ, and what it actually takes to deliver a consistent real time experience across both platforms.
You will leave with guidance on when these features are worth adopting, where platform parity breaks down, and how to design product and backend flows that work well for both iOS and Android in 2026.
Getting Your App Ready for Android's 16 KB Page Size Transition
With Android 15 introducing a 16 KB page size option, it’s essential to prepare your app to meet this new standard for both performance and compliance. This session breaks down the process into four essential parts:
Performance Gains: Learn how the 16 KB page size can improve launch times and app responsiveness.
Impact Evaluation: Discover methods to determine if this change affects your app and what modifications may be necessary.
Code Optimization: Discover techniques to align your code and binaries with the 16 KB page size requirement.
Testing Strategies: Gain insights into testing practices to confirm your app is fully compatible.
Prepare your app for the 16 KB page size requirement and stay ahead with a competitive performance edge.
Decoding OAuth and OpenID Connect for Mobile Developers
If you've not read RFC 8252 or found it overwhelming, fear not. I aim to break down this specification, distilling it into digestible key concepts that underscore your everyday work. RFC 8252 provides essential guidelines for implementing OAuth 2.0 in native applications, focusing on the unique security and usability challenges these apps face compared to their web counterparts.
The presentation is designed to demystify the intricate processes of OAuth, translating technical jargon into practical knowledge specifically for mobile developers. I will introduce the fundamentals of OAuth, highlighting its importance in the architecture of mobile applications. This will set the stage for a deeper exploration of the various types of tokens used in OAuth.
We will explore ID Tokens, Access Tokens, and Refresh Tokens. We'll delve into their distinct functions, examine their payloads and claims, and understand how they collectively ensure a secure application experience. I will address the differences among various token types, the nuances of authentication versus authorization, the nature of different grant types, and the methods for validating tokens.
By the end of this session, attendees will have a solid grasp of RFC 8252's guidelines and a better understanding of how to effectively implement OAuth 2.0 in their native applications.
Pruning Your App: Good Practices for Reducing App Size
App size reduction should be a critical aspect of app development, and is especially necessary for end users who may have restricted device storage or limited data plans. However, it can be challenging for developers—especially those working with multiple contributing teams—to manage and visualize app size throughout the development flow.
Using the major telecom company app, Xfinity, as an example, we will take a deep dive into how to optimize app size. This app illustrates the complexities of size management: the app is used across the world in both high- and low-resourced contexts, requires multi-language support, and draws visual assets from regional partners.
This presentation will address the following tools and techniques, many of which have been used in the Xfinity development flow, and are broadly applicable to other development projects:
Image compression: Using lossless compression with modern formats (.webp, vector graphics)
Unused code and assets: Implementing code shrinkers (Google’s R8)
Modularizing app delivery: Dividing the app into smaller modules, downloaded on-demand as per user needs (Google’s Dynamic Feature Delivery)
Strings: Improving string usage, including considerations for localization
Analysis: Monitoring app size throughout the development process
Mobile Sensors: Increasing Developers' Environmental Awareness
During this session, Android developer Chrystian Vieyra and physics educator Rebecca Vieyra will describe how developers can enhance mobile app development by connecting with environmental data through in-device sensors. Attendees will learn the basic operating principles for common sensors (accelerometer, gyroscope, magnetometer, barometer, microphone, etc.) as well as development opportunities with newer sensors (Google ARCore, time-of-flight). Participants will also discuss how to retrieve, filter, and make meaning of data. Special attention will be afforded to comparing the use of raw data against Google’s custom APIs that use sensor fusion. The speakers will also provide a brief introduction to a special case scenario of mobile app sensor integration funded by the U.S. National Science Foundation–the incorporation of sensors into Google ARCore visualizations, such as the use of magnetometer data to display three-dimensional magnetic fields in real space.
Keywords: Sensors, Google ARCore
A deep dive into deep links
Deep links are an integral tool to drive users directly to specific screens within your mobile app, entering potential and returning users into a desired action flow. However, deep links can be challenging to implement because developers must manage non-typical points of entry to the app (e.g., entering the app without launching a home screen) while also managing the app’s back stack.
Using the Xfinity app as an example, we will explain how deep links work and describe the process behind creating them. We will also explore the difference between a deep link and an app link, how to associate a website to a mobile app, and how to make an app react to deep links. We will address more advanced concepts, such as:
• Testing deep links via Android Debug Bridge (adb) and Android Studio
• Debugging deep links
• Typical navigational patterns when receiving deep links
• Handling extra parameter additions to deep links
• Using custom schemas
ARCore: Visualizing the Invisible
In this session, participants will learn about a National Science Foundation-funded project to develop a smartphone app to visualize magnetic fields with AR. The developers will discuss the opportunities and challenges of working with ARCore and provide visual examples from their recently-developed project, Physics Toolbox AR. They will share their experience of using ARCore in an educational research setting to help learners make sense of fields in 3-D space. Participants will be welcomed to explore the app during an interactive portion of the session. Learn more about this project at https://www.vieyrasoftware.net/physics-toolbox-ar
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Chrystian Vieyra Cortes
Director of Engineering
Washington, District of Columbia, United States
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