Vibe Coding a macOS App in Xcode 27 | Build a JSON Formatter from Scratch

Vibe coding has evolved rapidly, and Xcode 27 makes working with coding agents more capable than ever. In this video, I demonstrate the workflow I use to build a real macOS application while staying firmly in control of the development process.

Rather than letting an AI agent generate an entire application unattended, I use Codex as a development partner. You’ll see how I start in Plan Mode, review and approve each implementation stage, verify every change, and guide the agent through bug fixes and UI improvements until the application is complete.

Together we’ll build a macOS JSON Formatter from scratch that can:

• Validate JSON entered manually

• Open existing JSON files• Support drag-and-drop

• Display helpful error locations for malformed JSON

• Export formatted JSON files

• Copy formatted JSON to the clipboard

• Archive and export a signed macOS application

Along the way you’ll also learn:

• How to configure AI coding agents in Xcode 27

• How to export and use Xcode’s built-in agent skills

• Why planning before coding produces better results

• How to iterate with Codex instead of simply accepting generated code

• How to troubleshoot AI-generated bugs\

• How to create an app icon using Icon Composer

• How to generate a README with AI

• How to archive and export a macOS app for distribution