Building a Simple Mobile App with Kotlin Multiplatform

Kotlin Multiplatform allows you to write code that can be shared between multiple platforms, including Android and iOS. In this guide, we'll walk you through the steps to build a simple mobile app using Kotlin Multiplatform.

Setting Up Your Environment

Before you start, make sure you have the following tools and software installed:

• Kotlin (JVM)
• Kotlin Multiplatform Mobile (KMM)
• Android Studio (for Android development)
• Xcode (for iOS development)

Creating a Kotlin Multiplatform Project

Let's create a basic Kotlin Multiplatform project for a simple mobile app:

1. Create a new Kotlin Multiplatform Mobile project using the KMM plugin in your IDE or the command line. Specify the project name, organization, and other settings as needed.

2. In the project structure, you'll find common code shared between Android and iOS, Android-specific code, and iOS-specific code.

3. Define a common module with shared code, for example, `SharedCode.kt`:

class Greeting {
    fun greeting(): String {
        return "Hello from Kotlin Multiplatform!"
    }
}
    

This common code will be used by both the Android and iOS parts of the app.

4. Create Android-specific code to display the greeting on Android, for example, `MainActivity.kt`:

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
import shared.Greeting
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val greeting = Greeting()
        textView.text = greeting.greeting()
    }
}
    

This code sets up an Android activity and uses the shared `Greeting` class to display a greeting in the UI.

5. Create iOS-specific code to display the greeting on iOS. The process for iOS development may vary depending on your setup, but you'll use the shared `Greeting` class similarly to Android.

Running Your Mobile App

Now, you can run your mobile app on both Android and iOS:

1. For Android, open the project in Android Studio and run it on an emulator or physical device.

2. For iOS, open the project in Xcode and run it on a simulator or physical iOS device.

Conclusion

Building a simple mobile app with Kotlin Multiplatform allows you to share code and logic between Android and iOS. This example demonstrates the basics, but you can expand it to include more complex features, user interfaces, and platform-specific code as needed.

Happy coding with Kotlin Multiplatform for mobile app development!