First App.
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CHAPTER 04Lesson 11 of 36

Ask Codex for a plan

Let Codex understand the job before it starts changing files.

In Codex6 min read & do
By the end of this lesson

Agree a small plan that matches your idea and the project you created.

Let’s do this

  1. 1
    In Codex

    Open the existing project conversation

    Check the folder name first. Use the same project you created in Xcode. Tell Codex your app’s job and starting features, or use the message below.

  2. 2
    In Codex

    Ask for the plan first

    Ask Codex to explain the screens, the main action and how it will test them. Tell it to use the existing native SwiftUI project and begin with local data. If the app needs an online service, it should explain why and the cost before adding it.

  3. 3
    In Codex

    Check the behaviour, not the code

    Read the plan like a shopping list. Does each item belong in your small first version? Ask what any unfamiliar item does. Remove extras you did not ask for.

  4. 4
    In Codex

    Approve one useful step

    Once the plan matches your idea, tell Codex to build only the first screen next. Ask it to tell you which files changed and how to try the result. Keep unrelated files outside the project untouched.

The First App worksheet filled with a sample gardening app idea and three small features.View larger
This guide’s worksheet with a made-up gardening example. Use your own app idea; you can change it later. Captured 7 September 2026.Screenshot source (opens a new tab)

A message for Codex

I am building my first iPhone app for the people I want to help to [describe the problem my app should solve]. The starting features are [choose up to three small features]. Inspect the existing Xcode project. Propose a short plan using native SwiftUI and local storage where needed. Include the screens, the first useful action and how we will test it. Explain any new service, dependency or cost before adding it. Ask me one question at a time. Wait for me to approve the plan before editing files.

Make this message fit your idea.

What you should see

The plan describes your app in words you recognise. You have agreed what the first screen will contain.

If you get stuck

Go at your own pace. There is no test to pass.

Checked 7 September 2026. Screens can change; the official guides below have the latest steps.

Official Codex setupProjects in Codex