Two Major Codex Updates: Remote Mac Control from Phone & iOS Development Without Xcode

Introduction

OpenAI's Codex recently received two significant updates that make developers' workflows more flexible. The first enables remote Mac control from a phone, and the second allows iOS app previewing without Xcode through a plugin. Together, these features are changing how iOS developers work day-to-day.

OpenAI Codex is an AI programming assistant built on GPT large language models, originally well-known as the underlying engine for GitHub Copilot. In 2025, OpenAI upgraded Codex into a standalone Cloud Software Engineering Agent — no longer just a code completion tool, but one capable of autonomously executing complete development tasks in a sandbox environment, including reading codebases, writing code, running tests, and submitting PRs. Codex runs on OpenAI's cloud infrastructure, with each task executing in an isolated virtual machine to ensure security and reproducibility.

Remote Mac Control from Phone: Operate Your Computer Anytime, Anywhere

Connection Method

Codex has updated its "mobile remote control" feature. Users can open ChatGPT on their phone, access the Codex option through the sidebar, and establish a connection with their desktop. Connection methods include scanning a QR code or authorizing directly within ChatGPT.

Once connected, a small green dot appears on the phone, indicating a successful connection to the Mac device. The entire pairing process is streamlined and takes just a few steps.

Background Control While Screen Is Locked

The most interesting aspect of this feature: even when the Mac's screen is locked, Codex can still operate in the background. Users need to enable "Computer Control" permissions in settings and turn on the "Allow operation while locked" option.

Codex's "Computer Control" feature is essentially based on OpenAI's Computer Use capability — a technology that lets AI visually recognize screen content and simulate mouse clicks and keyboard inputs to operate graphical interfaces. Unlike traditional RDP (Remote Desktop Protocol) or VNC, this remote control isn't simple screen mirroring. Instead, the AI agent completes tasks through a screenshot-understand-act loop. The phone serves as the command terminal, while the actual screen understanding and operational decisions are made by the cloud-based AI model.

In actual testing, asking Codex to open NetEase Cloud Music and play a song while the screen was locked showed that although the screenshot function failed every time, it could indeed access and operate the app. After unlocking the system, NetEase Cloud Music was confirmed to have been successfully opened.

It's worth explaining that macOS doesn't completely stop running when the screen is locked — system processes and authorized background services continue to function normally. Codex leverages macOS's Accessibility API and automation frameworks, which can continue executing operations when the user session is locked, provided appropriate permissions are granted. However, the screenshot failure during lock screen is reasonable — macOS restricts screen capture-related API calls (such as CGWindowListCreateImage) when locked for security reasons. This is a system-level security policy, not a Codex bug.

Comparison with Similar Remote Control Products

From a functional positioning perspective, this is essentially a remote control solution that keeps the Mac in a non-sleep state. Compared to traditional remote control tools, Codex performs better in terms of precision and ease of use. From a quota consumption standpoint, the usage cost is also within an acceptable range.

iOS Builder Plugin: Breaking Free from Xcode

Plugin Installation & Core Features

The second update is Codex's new "iOS Builder" plugin. Users simply search for "iOS Builder iOS App" in the plugin marketplace to find and install it. Once installed, developers can preview iOS apps directly in Codex without launching the massive Xcode.

To understand the significance of this update, you need to know Xcode's role in iOS development. Xcode is Apple's official integrated development environment (IDE) and the core tool for iOS/macOS app development. It integrates a code editor, Interface Builder for UI design, Instruments for performance analysis, iOS Simulator, and code signing and app distribution tools. Xcode's installation package typically exceeds 30GB, launching and indexing large projects often takes several minutes, and it consumes enormous Mac memory and CPU resources. This is why being able to bypass Xcode for direct app previewing is so attractive to developers — it dramatically lowers the barrier to rapid iteration.

The plugin provides four core capabilities:

Build & Debug — Helps developers quickly build a first version and debug it
Fix Bugs — Opens a preview window directly to view fix results in real-time
Vulnerability Detection — Systematically catches potential vulnerabilities to ensure no bugs block release
Performance Analysis — Evaluates the app at the performance level

Actual Development Experience

In a demonstration, asking Codex to develop an iOS app resulted in a first version of code being written quickly. When using the plugin, selecting "Builder iOS" and requesting a build preview launches the simulator and maps the display to a browser.

This design approach is quite clever — since Codex's "Control Computer" plugin can already operate browsers, mapping the simulator to a browser allows the AI to directly perform autonomous review and interaction with the app, creating a closed-loop development-testing workflow.

Users can also operate manually, with each workspace supporting free modifications. In testing, after asking Codex to beautify the page, the app's basic functions (such as playlist recognition and page navigation) all worked properly. However, in actual development, you should provide more detailed requirement descriptions rather than vague instructions like "make it prettier."

Technical Implementation Logic

The plugin's implementation principle isn't complex: it maps Apple's official iOS Simulator to an external application (browser), then combines Codex's computer control capability for interaction. When the simulator is closed, the browser-side preview exits accordingly. Users can also freely select different iPhone models for simulation.

From a technical perspective, iOS Simulator is a simulator tool bundled with Xcode that emulates the iPhone/iPad runtime environment on Mac (note: this isn't hardware emulation, but rather compiling iOS frameworks as x86/ARM Mac native code). Technical approaches for mapping simulator display to browsers typically include: transmitting simulator screen frame data via WebSocket, or using noVNC and other web-based VNC clients for real-time display transmission. The cleverness of this approach lies in the fact that browsers are one of the environments Codex's Computer Use capability handles best, so after mapping, the AI can operate the iOS app interface just like operating a webpage.

Limitations

It's important to note that while you can complete development and previewing in Codex, actually publishing an app to the App Store still requires paying Apple's $99 annual developer fee. This is a hard barrier in the Apple ecosystem that no tool can bypass.

Specifically, the Apple Developer Program's $99/year fee isn't just a ticket to publish apps on the App Store. It also includes: access to TestFlight for beta test distribution, using App Store Connect to manage apps, obtaining advanced API permissions (such as push notifications, CloudKit, Sign in with Apple, etc.), and certificates for real device debugging. Starting in 2024, the EU allows sideloading due to the Digital Markets Act (DMA), but in all other global markets, the App Store remains the only official channel for iOS app distribution.

Practical Significance for Developers

The combination of these two updates paints a completely new work scenario for iOS developers: you can remotely launch Codex tasks on your Mac from your phone, letting AI autonomously complete code writing, build previewing, and bug detection — without even needing to sit in front of your computer. For developers who've long suffered from Xcode's slow startup and resource consumption, this is genuinely a liberation in terms of efficiency.

Of course, this solution is currently better suited for rapid prototype validation and simple app development — complex large-scale projects may still require Xcode's complete toolchain. But as a supplement to the development workflow and an efficiency-boosting tool, these Codex updates are undoubtedly heading in the right direction.