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World Congress 2026 Europe β€’ Jul 9, 2026 β€’ Session details

JSX to Live Activity: The Story of Voltra

Szymon Chmal

Build iOS Live Activities and Android widgets without touching Swift or Kotlin. Discover how Voltra overcomes Apple's 4KB limit to deliver server-driven UI updates entirely in JSX.

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#1 about 3 min

Introduction to Voltra and native Live Activities

The origin story of Voltra reveals how to bridge React with iOS extensions natively.

#2 about 4 min

Writing Live Activities using Voltra JSX

Familiar React principles and JSX components render widgets via server data with native hot reloading.

#3 about 2 min

Translating React trees to native UI frameworks

Voltra processes the React element tree hierarchy to reconstruct interfaces using platform primitives directly.

#4 about 2 min

Building a custom React renderer with Reconciler

The React Reconciler package configures hook support and concurrent mode functionality inherently.

#5 about 2 min

Mapping primitive elements to SwiftUI equivalents

Primitive JSON representations reconstruct corresponding SwiftUI components and properties during native evaluation.

#6 about 2 min

Bridging React Native styles with SwiftUI modifiers

React Native style objects require transformation into compatible SwiftUI string modifiers and simulated margins.

#7 about 2 min

Overcoming the payload limit for Live Activities

Multiple dynamic island structural variants must fit strictly within Apple's tiny data bandwidth limit.

#8 about 4 min

Compressing and deduplicating React payloads for native

Brotli compression, prop dictionaries, and object reference deduplication maximize extremely constrained payload limits.

#9 about 4 min

Implementing server-side rendering to push UI updates

A scratch-built traversal renderer avoids unhandled hook errors and resolves one-pass static snapshots.

#10 about 4 min

Rebuilding React hooks via secret internal dispatchers

Undocumented internal React dispatchers allow mocked hook executions specifically for static server environments.

#11 about 3 min

Advanced features and cross-platform architecture in Voltra

Platform parity involves preloading images, mapping layout engines, and executing dynamic chart generation.

#12 about 8 min

Push notification limits and experimental rendering architectures

Apple push service restrictions shape architectural limits while experimental Javascript VMs explore widget decoupling.

Matching moments

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Defining native applications and the history of React

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Architecture and performance optimizations in React Native

Marc Rousavy Marc Rousavy Β· WWC 2025

2:25 min

Origins and architectural capabilities of the React Native framework

Edoardo Dusi Β· LIVE

4:30 min

Tracking open source community trends in JavaScript native frameworks

Dan Cranney +2 Β· LIVE

3:25 min

Accessing native primitives for advanced layouts and APIs

Xuan Huang Xuan Huang Β· WWC 2025

5:38 min

Core differences between React Native and Flutter

Simon Auer Simon Auer Β· WWC 2022

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