The explosion of Large Language Models (LLMs) has changed what users expect from a chat interface. Gone are the days of waiting for a spinning loader to finish. Modern AI apps feel alive—they stream responses token by token, mimicking a real-time conversation.

But how do you build a UI that stays buttery smooth while receiving dozens of updates per second? The answer lies in the synergy between SwiftUI’s declarative paradigm and the Observation framework .

In this guide, we’ll dive into the reactive foundation of AI chat interfaces, exploring how to handle asynchronous data streams and build a high-performance chat bubble UI that scales.

The Reactive Foundation for AI Chat

Traditional apps work on a request-response cycle. AI apps work on a streaming cycle .…