How to Build an iPhone and Android App from a Description, Step by Step

How do I build an app by describing it?

Open RNBlocks Studio, describe who the app is for and the main thing they should be able to do, and send it. RNBlocks generates a React Native and Expo app you can try in an iOS or Android preview. Then ask for focused changes in the same conversation, connect services such as Supabase when the app needs saved data, test the main task, and choose Publish when it works.

1. Describe a clear first version

Try this prompt, or replace the audience and task with your own:

Build a travel app to discover destinations, save favorite places and plan a trip. Use inviting photography and clear navigation. Start with Explore, Destination and Saved screens.

A good first prompt names the audience, the main task, the screens, the data that should be saved and any services like AI answers.

2. Connect saved data when requested

A local favorites list and an account that syncs across devices are different features. If you need sync, say so. The agent asks to connect Supabase; complete the setup and return to the same conversation.

3. Try the app

Choose Preview, then iOS or Android. Complete a real task: open a destination, save it, find it in Saved, then close and reopen the app.

4. Ask for one focused change

"Make the destination title easier to read over the photo." Then repeat the same task.

5. Move into publishing

When the main task works, choose Publish and tell the publishing agent what you want, for example: "Help me prepare this app for iPhone testing. Check what is missing and tell me which accounts I need."

Cost

New accounts get 100 promotional credits with no card required. Pro is $15/month with 150 credits; Studio is $29/month with 400.

Start with a single journey you can recognize

For a travel app, a useful first brief is: 'Help people discover places for a weekend trip. Show a place list, a detail screen and a saved list. Let me save a place and reopen it later. Start with sample places and leave bookings out.'

This gives the agent a task and a boundary. 'Make a travel app like all the popular ones' leaves important decisions unresolved and can produce screens you did not need.

Say which information is real

Sample content helps you judge layout quickly. It does not establish that accounts, search or saving are connected to live services. Ask where the information comes from and what should persist.

For the first version, you might keep saved places on the phone. If you want them on another device, request accounts and cloud saving explicitly. That introduces backend setup and access rules.

Review the generated result in order

First check navigation. Can you open a place and return? Next check actions. Does Save change the intended list? Then check persistence. Is the place still there after reopening? Finally review spacing, typography and images.

This order avoids polishing a screen around behavior that will need to change. It also gives you clearer follow-up requests.

Keep changes focused

A useful follow-up is: 'On the place detail screen, move Save above the description and keep the existing colors and navigation.' A bug report should include the steps, actual result and expected result.

If a change affects an unrelated area, say what changed and ask to restore that behavior. Check the latest result before repeating a request, so you do not accidentally ask for duplicate work.

Add services when the feature calls for them

Connect Supabase for supported account and data workflows, or an AI provider for a defined feature. Use the private connector form for credentials. A provider connection is configuration; the feature still needs a successful request and appropriate access controls.

Test with representative data and two accounts when information is private. Keep real customer details out of public examples and prompts.

Move from preview to release deliberately

Try the app in the relevant previews, then on a phone using a supported development route. For features outside Expo Go, use an appropriate installed build.

When the main journey works, choose Publish and describe the next goal: testing on a device, inviting beta testers or preparing a store release. These are separate milestones.

You can begin without writing code, but you still decide what the app should do and check its results. A strong first session ends with a small journey you can use, rather than a long list of generated screens you have not tested.

How detailed should the first prompt be?

Give enough detail to define the main task, data and important visual direction. A concise paragraph can be better than pages of unrelated features. Include what should wait until later so the first result stays focused.

Can I build from an image instead?

Use an image as a reference and explain what the controls should do. A screenshot can show appearance but not whether information syncs, who may edit it or what happens after a failed save.

Do I need an account service immediately?

Only when the task requires it. A local prototype can help test layout and navigation. When you promise cross-device saving or private shared data, add and verify the backend behavior.

How do I keep the app consistent while editing?

Name the screen and change, and say which existing behavior should remain. Review the result before making another request. Use the same example data and task so changes are easier to judge.

What should I do after the first working journey?

Try it on the intended device, check ordinary errors and show it to someone who fits the audience. Use their observed difficulty to choose the next change. When release becomes the next goal, continue with the publishing workspace rather than assuming a preview link is already an installable app.

Build it with RNBlocks

Start free in RNBlocks with the travel-app brief or your own equally specific task. Build, connect and refine it with our agent. When the journey works on the intended devices, continue in Publish to prepare screenshots, builds and the relevant store steps.