First App.
Your learning space A little progress, every day
CHAPTER 05Lesson 17 of 36

Use skills and ready-made parts

Reuse good instructions and well-made parts when they solve a real problem.

In Codex5 min read & do
By the end of this lesson

Know when a skill or a library helps, and when it adds unnecessary setup.

Let’s do this

  1. 1
    In Codex

    Start with the built-in parts

    Most first iPhone apps can use Apple’s own buttons, lists, navigation and storage. Ask Codex to check those before adding a new package. A package or library is a set of code someone else maintains.

  2. 2
    In Codex

    Use a skill for a specific job

    A skill gives Codex a reusable set of instructions, such as reviewing a design or checking accessibility. Ask what relevant skills are already available. Their names depend on the installation; do not assume you have the same ones as someone else.

  3. 3
    In Codex

    Check a suggested addition

    Before installing, ask who maintains it, what it does, whether it is free for your use, which permissions it needs and how often it is updated. Codex should explain why the app’s existing tools are not enough.

  4. 4
    In Codex

    Keep the result easy to maintain

    If a package is necessary, let Codex add it through Xcode’s normal package tools and record the version. Run the app again. If it is unnecessary, leave it out rather than installing it just because it is popular.

OpenAI’s setup guide showing the menu for choosing Codex in the ChatGPT desktop app.View larger
Screenshot of OpenAI’s official setup guide, captured 7 September 2026. The guide’s interactive illustration shows where to choose Codex.Screenshot source (opens a new tab)

A message for Codex

For my first iPhone app, check whether an available design or accessibility skill would help with our current screen. Explain what it does before using it. Prefer native Apple components. Before adding any external package or plugin, tell me its purpose, official source, licence, cost, permissions and maintenance status, and wait for my approval.

Make this message fit your idea.

What you should see

You can explain what a proposed extra part does and why your app needs it. You have not installed a pile of tools you cannot name.

A couple of words, explained

Skill
Reusable instructions that help Codex perform a particular kind of task.
Library
Ready-made code your app can use instead of rebuilding the same part.

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.

Skills and project instructionsApple’s design guidance