Step 1: Define one problem and one user
Start with a single sentence: who uses the app, and what it helps them do. “Clients of a hair salon book and change appointments without calling” is a usable start.
Talk to 5 to 10 people who match that user before anything else. If they already solve the problem with a spreadsheet, a group chat or a phone call, you know what the app has to beat.
Step 2: Scope a small first version (MVP)
A minimum viable product (MVP) is the smallest version that solves the main problem. List every feature you want, then keep only the 3 to 5 that the main task can’t work without.
Everything else goes to a later list. A small first version reaches the App Store sooner, costs less and shows what your users actually use.
Step 3: Choose how to build your app
You have four main options, and each fits a different budget and goal.
| Option | Good for | Watch out for |
|---|---|---|
| AI app builder (Lovable, Bolt, Rork) or AI editor (Cursor) | Testing an idea in days, with little money | App Review rejections, code you can’t maintain, payments and privacy gaps |
| Freelance developer | A small, well-defined app | One person covers design, code and publishing, and may move on after launch |
| App development studio | A first version with design, code, publishing and maintenance in one contract | Higher upfront price; compare the list of stages in each quote |
| In-house hire | Apps that are the core of your business and change every week | Salary and recruiting time before the first line of code |
You can also mix them: test the idea with an AI tool, then hire a studio for the version that goes to the App Store. The page on AI-built apps on the App Store covers that route.
Step 4: Choose native or cross-platform
A native iPhone app is written in Swift, Apple’s language, and uses iPhone features directly. A cross-platform app shares one code base between iPhone and Android.
Native fits apps that rely on iPhone features or need to feel fast every day. Cross-platform fits apps that must launch on both platforms at once with one budget. The page on iOS and Mac app development explains the native route.
Step 5: Design the main screens
Before code, draw the screens of the main task: from opening the app to finishing it. Paper sketches or a design tool both work.
Apple’s Human Interface Guidelines describe how iPhone apps look and behave. Following them makes your app easier to use and easier to approve.
Step 6: Build and test with TestFlight
Development runs in short cycles, with a new build every week or two. Each build goes to TestFlight, Apple’s beta testing app.
With TestFlight you install the app on your own iPhone and invite up to 10,000 external testers by email or public link. Each build stays available for 90 days. The first build for external testers goes through a review by Apple.
Step 7: Publish on the App Store
To publish, you need an Apple Developer account ($99 per year), an app record in App Store Connect and a complete store listing. Then Apple’s App Review team checks the app against its guidelines.
Apple says it typically reviews 50% of submissions in under 24 hours and 90% in under 48 hours. The guide on how to publish an app on the App Store lists each step, and the Apple Developer account guide explains enrollment.
Step 8: Plan for maintenance from day one
An app is never finished. Apple releases new versions of iOS every year, and since April 28, 2026, uploads must be built with Xcode 26 or later.
Set aside a budget for updates, fixes and your backend. The page on app development cost lists the recurring costs after launch.
A realistic timeline. In the market, a first version usually takes 3 to 4 months, from scope to App Store. Add time for App Review questions on the first submission.
Common mistakes when building an app
These four mistakes cost the most time and money.
- Too many features in version 1. The app takes longer, costs more and launches without feedback.
- No account deletion or privacy policy. Apple requires both when users can create an account.
- No plan after launch. Without maintenance, the app breaks with the next iOS release.
- The code and accounts in someone else’s name. Make sure the Apple Developer account and the code belong to you or your company.
How Carvalho Karsten can help you build your app
Carvalho Karsten builds native iPhone and Mac apps in Swift, from scope to the App Store. The work starts with a project review of your idea, your users and your integrations.
You get the stages, timeline and price of each stage in writing. If you already have a prototype, the review shows what can stay. Send a short description of your app and request a project review.