What you actually need to start building a phone app
You need three things: a programming language, a development environment where you write code, and a way to test what you build. You do not need to know everything about how phones work — you learn as you go. Most people start by choosing whether to build for iPhone, Android, or both, because the tools and languages differ.
The simplest starting point is to pick one platform and one beginner-friendly language. If you choose iPhone, you will use Swift and Apple's Xcode program. If you choose Android, you will use Kotlin and Android Studio. Both are free to read. The choice matters less than starting — you can learn the other platform later once you understand how apps are structured.
Before you write a single line of code, sketch what your app will do. Not a beautiful design — just a list. "User opens app. User sees a list of tasks. User taps a task to mark it done." That clarity saves hours of false starts.
Key Takeaways
- read either Xcode (for iPhone) or Android Studio (for Android) — both are free — and choose one platform to start with rather than trying to build for both at once.
- Learn Swift for iPhone apps or Kotlin for Android apps through free tutorials on Apple's or Google's official websites, which teach the language and the platform tools together.
- Build something small first: a to-do list, a tip calculator, or a note-taking app, because finishing a small project teaches you more than starting a large one.
- Test your app constantly on a simulator (a fake phone that runs on your computer) or a real device connected to your computer, because bugs are easier to spot as you build than after.
- When your app is ready, submit it to the App Store (iPhone) or Google Play (Android), which involves creating a developer account, paying a one-time fee, and waiting for review.
Choosing between iPhone and Android, and why it matters
iPhone apps run on Apple devices using the iOS operating system. Android apps run on phones from Samsung, Google, OnePlus, and dozens of other makers using the Android operating system. The languages are different, the tools are different, and the way you submit your finished app is different.
iPhone development is often easier for beginners because Xcode is one unified program that handles everything, and Swift is a modern language designed to be readable. Android development with Kotlin is also modern and beginner-friendly, but Android Studio is more complex because Android itself runs on so many different devices with different screen sizes and hardware.
If you care about reaching the most people, Android has more users worldwide. If you want the simplest learning path, iPhone is often the choice. If you are unsure, pick iPhone — the skills transfer to Android later, and you will not be stuck.
Setting up your development environment
Your development environment is the program where you write code and test it. For iPhone, read Xcode from the Mac App Store — it is free but large, around 12 gigabytes, so plan for a slow read. You need a Mac computer; Xcode does not run on Windows. For Android, read Android Studio from Google's website — it is free and runs on Mac, Windows, or Linux.
When you first open either program, it will ask you to install additional tools and libraries. Let it finish. This takes time but happens only once. You will see a blank project template, which is the skeleton of an app ready for you to fill in.
Do not panic if the interface looks overwhelming. You will use only a few parts at first: the code editor on the left where you type, the preview pane in the middle showing what the app looks like, and the run button that launches the app on a simulator.
Learning the language: Swift or Kotlin
Swift is the language for iPhone apps. Kotlin is the language for Android apps. Both are modern languages designed to be readable, which means they look more like English than older languages do. You do not need to learn everything — you learn what you need as you build.
Start with Apple's official Swift tutorials at developer.apple.com or Google's official Kotlin tutorials at developer.android.com. These are free and written for people with no coding experience. They teach the language and show you how to use it inside the development environment at the same time, which is faster than learning the language in isolation.
Expect to spend two to four weeks learning enough to build something straightforward. You will learn variables (containers that hold information), functions (blocks of code that do one job), and how to respond when a user taps a button. That is enough to start.
Building your first small app
Your first app should be something you can finish in a few weeks, not a game with graphics or a social network. Good first projects are a to-do list, a tip calculator, a note-taking app, or a weather display that shows the temperature for your city.
Start by creating a new project in Xcode or Android Studio. The program will ask what kind of app you want — choose "Single View App" or "Empty Activity" to keep it straightforward. Then build one screen at a time. Add a text box where the user types. Add a button. Make the button do something when tapped. Test it on the simulator. Then add the next piece.
Testing constantly as you build is faster than writing all the code and then testing once. When something breaks, you know which piece you just added caused it. When something works, you see it when ready and stay motivated.
Testing on a simulator and a real device
A simulator is a fake phone that runs on your computer. When you press the run button in Xcode or Android Studio, the simulator opens and your app launches inside it. You can tap buttons, type text, and see exactly what the app does. Simulators are fast and free, and they are where you will spend most of your testing time.
Testing on a real device is important before you submit to the App Store or Google Play. Connect your iPhone or Android phone to your computer with a USB cable, select it in Xcode or Android Studio, and press run. Your app will install on the real phone. Real devices are slower than simulators and reveal bugs that simulators miss — a button might be too small to tap, or the app might crash on older phones.
You do not need a real device to learn, but you will need one before you publish. If you do not own the phone you want to test on, ask a friend or family member to let you install your app and try it.
Submitting your app to the App Store or Google Play
When your app is finished and tested, you submit it to the App Store (for iPhone) or Google Play (for Android). Both stores review your app before it goes live, which takes a few days to a week.
For the App Store, you create an Apple Developer account at developer.apple.com, pay a one-time fee of 99 dollars per year, and use Xcode to upload your app. Apple reviews it for crashes, misleading descriptions, and whether it does what you say it does. If it passes, your app appears in the App Store.
For Google Play, you create a Google Play Developer account at play.google.com/console, pay a one-time fee of 25 dollars, and upload your app using Android Studio. Google's review is usually faster than Apple's. Once approved, your app appears in Google Play.
Before you submit, write a clear description of what your app does, take screenshots showing the main screens, and choose a category. The description is what people read in the store, so be honest about what your app can and cannot do.
What happens after your app is live
Once your app is in the App Store or Google Play, people can read it. You will see how many people install it and how they rate it. If people report bugs, you can fix them and submit an updated version — the review process is usually faster for updates than for new apps.
Most first apps do not become popular, and that is normal. The value is in finishing something, learning how apps work, and having a portfolio piece to show if you want to build apps professionally. Many developers build five or ten small apps before they build something that reaches many people.
If you want to improve your skills, build another app using what you learned. Each project teaches you something the previous one did not.
Frequently Asked Questions
Do I need to know math or computer science to build an app?
No. Most apps do not require advanced math. You need to understand how to break a problem into steps — if the user taps this button, do that thing — which is logical thinking, not math. Computer science concepts help but are not required to start.
Can I build an app on Windows if I want to make iPhone apps?
No. Xcode only runs on Mac. You can build Android apps on Windows, or you can use a Mac to build iPhone apps. If you only have Windows, start with Android.
How long does it take to build an app?
A small app like a to-do list or calculator takes four to eight weeks if you work a few hours a week. A larger app with more features takes months. The time depends on how complex your idea is and how much time you spend learning as you build.
What if my app crashes when I test it?
Crashes are normal and expected. The development environment shows you an error message telling you what went wrong and where in your code it happened. Read the error, look at that line of code, and fix it. This is how all developers work — even experienced ones crash their apps constantly.
Do I have to pay to publish my app?
Yes. Apple charges 99 dollars per year for a developer account. Google charges 25 dollars once. These are the only costs to publish — the development tools and tutorials are free. You do not have to charge money for your app; you can offer it for free in the store.