How to Build Android, iOS and Windows Apps? Beginner Guide 2026

Each platform handled on its own — what you need, which language, which software, and what the code looks like, all in one place.

"I really want to build an app, but where do I even start?" — I get asked this a lot. And the confusion makes sense, because you start reading about Android and halfway through iOS shows up, then Windows sneaks in, and by the end you can't remember which is which. So this time I've written it differently — everything you need to know about each platform (Android, iOS, Windows) sits in its own section. Finish one, then move to the next, and nothing gets tangled in between.

Android Apps — What You Need, Which Language, Which Software, and What the Code Looks Like

Let's start with Android, since it's the platform most people want to learn first. To build an Android app you need three things — a programming language, a piece of software to write the code in (this is called an IDE), and a way to build your layout. Let's take them one at a time.

Which language is used?

Android mainly runs on two languages — Kotlin and Java. Java is much older, and plenty of big companies still have their legacy codebases sitting in Java, so it hasn't disappeared. But Google itself has now declared Kotlin the official language — new features land in Kotlin first, and the documentation gives it priority too. If you're learning from scratch, starting with Kotlin is your best bet, though since the job market still asks for Java, it's worth circling back to it later.

Which software do you write the code in, and where do you get it?

What does the app structure look like?

When you create a new project in Android Studio, these are the main files you'll find:

• MainActivity (in Kotlin or Java) — this is where the app's logic goes, like what happens when a button is pressed
• activity_main.xml — this is where the visible part (the layout) is built, deciding where the buttons and text sit

The two files work side by side — the XML decides what you "see", and the Kotlin/Java decides what "happens". Let's look at the code for all three below.

What does the code look like?

Below is a small example that shows a message when a button is pressed. Use the buttons at the top to switch between Java, Kotlin and XML — you can compare what the code looks like in whichever language appeals to you. "Copy" copies whatever code is currently showing.

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button myButton = findViewById(R.id.myButton);
        myButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button Clicked!", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val myButton = findViewById<Button>(R.id.myButton)
        myButton.setOnClickListener {
            Toast.makeText(this, "Button Clicked!", Toast.LENGTH_SHORT).show()
        }
    }
}

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello!" />

    <Button
        android:id="@+id/myButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click Me" />

</LinearLayout>

If you look closely at the Java and Kotlin code, you'll notice they do exactly the same job — the only difference is how they're written, with Kotlin coming out shorter and cleaner. The XML, on the other hand, isn't really logic at all; it just says "put this button here".

So how do you actually build the app? (Step by Step)

1. Settle on an idea: start small, something like a to-do list app.
2. Install Android Studio: the way described above.
3. Be patient the first time you open it: the setup wizard downloads the Android SDK by itself.
4. Create a new project: "New Project" → "Empty Activity" → give it a name → pick Kotlin or Java as the language → "Finish".
5. Wait for the Gradle sync: the first one takes 2–5 minutes, which is perfectly normal.
6. Build the layout: put code like the sample above into activity_main.xml.
7. Write the logic: put code like the sample above into MainActivity.
8. Set up an emulator: "Device Manager" → "Create Device" → pick any phone model.
9. Run it: press the green ▶️ button and your app shows up in the emulator.
10. Publish it: once it's ready, upload it through the Google Play Console ($25, one time).

iOS Apps — What You Need, Which Language, Which Software, and What the Code Looks Like

Now let's turn to iOS. The first and most important thing here is a warning — to build iOS apps you must have a Mac computer. There's no route to building iOS apps on Windows or Linux, because Apple's software simply never comes to Windows. Not knowing this before you start can cost you a lot of wasted time, which is exactly why I'm saying it up front.

Which language is used?

On iOS, Swift is the current standard — Apple built it themselves, and pretty much everyone uses it. There's an older one called Objective-C, but you barely see it in new projects anymore, so beginners don't need to spend time on it.

Which software do you write the code in, and where do you get it?

What does the app structure look like?

When you create a new project in Xcode, this is mainly what you get:

• ContentView.swift — both the logic and the layout are written here together (no separate XML file like Android, because SwiftUI lets you build the layout inside the code itself)

What does the code look like?

Below is the same button-click example in Swift, and after it I've put the layout in a separate tab so it's a bit clearer to see.

import SwiftUI

struct ContentView: View {
    var body: some View {
        Button("Click Me") {
            print("Button Clicked!")
        }
        .padding()
    }
}

VStack {
    Text("Hello!")
    Button("Click Me") {
        print("Button Clicked!")
    }
    .padding()
}

The difference here is that on Android you have to build your layout in a separate XML file, whereas SwiftUI on iOS lets you write the layout right inside your Swift code — it feels a little odd at first, but as you practise you may find it's actually the faster approach.

Windows Apps — What You Need, Which Language, Which Software, and What the Code Looks Like

Last, let's talk about Windows desktop apps — a slightly different world, since here you're building software that runs on a computer rather than a phone.

Which language is used?

C# is the most popular language here, used together with .NET. If you need high-performance software, C++ is used too, but that's a more advanced topic — beginners are better off starting with C#.

Which software do you write the code in, and where do you get it?

What does the app structure look like?

• MainWindow.xaml — the layout is built here (think of it like Android's XML)
• MainWindow.xaml.cs — the logic is written here (in C#)

What does the code look like?

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void MyButton_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show("Button Clicked!");
    }
}

<Window x:Class="MyApp.MainWindow">
    <StackPanel>
        <TextBlock Text="Hello!" />
        <Button x:Name="MyButton"
                Content="Click Me"
                Click="MyButton_Click" />
    </StackPanel>
</Window>

You can see the same pattern here — the XAML says what gets displayed, and the C# says what happens on click. Android's XML + Kotlin and Windows' XAML + C# come from almost the same line of thinking; only the names are different.

Need All Three at Once? Cross-Platform Options

Writing separate code for Android, iOS and Windows is obviously going to eat a lot of time. Cross-platform frameworks exist precisely to solve this, letting one codebase run your app on several platforms:

• Flutter (Dart language) — Google's, and the most talked-about right now. Download it here; it runs on Windows, Mac and Linux.
• React Native (JavaScript) — easy going if you already know web development.
• .NET MAUI (C#) — Microsoft's own answer.

From my own experience, Flutter is the gentlest of these for a beginner — the documentation is good and the community is big.

Quick Questions People Ask

Kotlin or Java — which should I learn?
Kotlin is the better choice, but knowing Java helps when you're job hunting, which is why I've given you the code for both above.

Can I build an iOS app on a Windows computer?
No. Xcode only runs on a Mac, so without one it isn't possible.

Can I build an app without knowing how to code?
No-code tools like Thunkable and Appy Pie handle the basics, but if you want something custom and reliable, learning to code is the lasting solution.

Not everything will click on the first read, and that's normal — every developer has walked this same road. Pick whichever platform appeals to you, install its software, copy the code above and run it yourself. That first attempt will teach you more than anything else.