From iOS to Android: A Step-by-Step Guide to Using Google's Migration Assistant

Overview

For nearly two decades, Android has dominated the global mobile operating system market, yet many popular apps still debut on iOS first, sometimes leaving Android users waiting months—or even forever—for a port. To bridge this gap, Google introduced the Migration Assistant, a developer tool designed to automate the conversion of iPhone apps into Android apps. This comprehensive guide walks you through the entire process, from initial setup to final testing, ensuring you can leverage this tool to bring your app to the Android ecosystem efficiently.

The Migration Assistant works by analyzing your iOS project (Xcode workspace or Swift/Objective-C code), mapping UI elements, APIs, and logic to their Android counterparts (Jetpack Compose, Kotlin, Java), and generating a fully functional Android project. While not perfect—some manual adjustments are required—it dramatically reduces the time and effort needed for cross-platform development.

Prerequisites

Before you begin, ensure you have the following:

• iOS Source Code: A complete Xcode project with Swift or Objective-C source files. The tool supports iOS 12 and later.
• Android Development Environment: Android Studio (Arctic Fox or newer) installed on your machine.
• Google Migration Assistant Plugin: Available from the JetBrains Marketplace (for Android Studio) or as a standalone CLI tool.
• Basic Knowledge: Familiarity with both iOS and Android development paradigms (e.g., UIKit vs. Jetpack Compose, CocoaPods vs. Gradle dependencies).
• System Requirements: At least 8 GB RAM, 10 GB free disk space, and an internet connection for dependency resolution.

Step-by-Step Instructions

1. Install the Migration Assistant Plugin

Launch Android Studio, go to File > Settings > Plugins (or Android Studio > Preferences > Plugins on macOS). Search for “Google Migration Assistant” and install it. Restart Android Studio to activate the plugin.

Alternatively, if you prefer the command line, download the CLI binary from the Android Developer site and add it to your PATH.

2. Prepare Your iOS Project

Clean up your iOS codebase to improve conversion accuracy:

• Remove any platform-specific dependencies not supported on Android (e.g., HealthKit, ARKit). The tool will flag these, but pre-removal reduces errors.
• Ensure your project compiles without errors in Xcode.
• Export your project as a .xcworkspace or .xcodeproj file. The tool also accepts individual source folders.

3. Initiate the Conversion

In Android Studio, go to File > New > Import Project from iOS. Select your iOS project file. The Migration Assistant will analyze the project structure and display a summary of detected components. Click Start Conversion.

If using the CLI, run:

migration-assistant --input /path/to/ios/project --output /path/to/android/project --language swift

The process may take several minutes depending on project size.

4. Review Generated Code

Once conversion completes, you'll see a new Android project in the output directory. Key mappings include:

• UI: SwiftUI views are converted to Jetpack Compose composables; UIKit storyboards become XML layouts (with manual Compose migration recommended).
• Business Logic: Swift functions transform into Kotlin functions; Objective-C methods become Java methods.
• Dependencies: CocoaPods entries are mapped to Gradle dependencies where equivalents exist (e.g., Alamofire → Retrofit).

Example: A Swift button handler

button.addTarget(self, action: #selector(buttonTapped), for: .touchUpInside)

becomes Kotlin

button.setOnClickListener { buttonTapped() }

5. Resolve Unmapped APIs

Open the generated ConversionReport.html file (saved in the output root). It lists all unmapped APIs with suggested alternatives. For example:

• iOS UIAlertController → map to Android AlertDialog or Material Design dialogs.
• iOS CoreData → Room or DataStore.
• iOS AVFoundation → MediaPlayer or ExoPlayer.

Manually replace these in the generated code. Use Android Studio's Find in Path to locate all instances.

6. Adjust Build Configuration

Open build.gradle (app module) and:

• Set minimum SDK: The tool assumes Android 5.0 (API 21) by default; adjust based on your target audience.
• Add any missing dependencies (e.g., implementation 'androidx.appcompat:appcompat:1.6.1').
• Configure Kotlin version if needed: kotlinOptions { jvmTarget = '1.8' }

7. Test and Iterate

Build the project (Build > Make Project). Fix compilation errors using the Build Output window. Common fixes include:

• Adding @JvmStatic to companion object methods.
• Changing nil to null in Kotlin.
• Replacing iOS-specific enums with Android equivalents (UIColors → Color).

Run the app on an emulator or device. Use Android Studio's Layout Inspector to compare UI alignment with the original iOS design.

Common Mistakes & How to Avoid Them

Ignoring the Conversion Report

The report is your best friend. Skipping it leads to runtime crashes. Always review every warning item, especially those marked “High Impact.”

Assuming One-to-One API Mapping

iOS and Android APIs differ in behavior. For instance, UserDefaults is synchronous, while DataStore uses coroutines. You may need to restructure logic to match Android's threading model.

Neglecting Permissions

iOS handles permissions at runtime with system dialogs; Android requires both AndroidManifest.xml declarations and runtime requests. The tool may miss some. Add <uses-permission android:name="android.permission.CAMERA" /> etc., manually.

Overlooking Resource Files

Images, fonts, and localized strings are not automatically copied unless they’re in the Assets.xcassets folder. Manually transfer them to res/, respecting Android's naming conventions (e.g., lowercase, no hyphens).

Incorrect Build Flavors

If your iOS project uses multiple targets or schemes, the tool may not replicate them. Recreate Android build variants manually.

Summary

Google's Migration Assistant offers a powerful shortcut for converting iOS apps to Android, cutting development time from months to days. By following this guide—installing the plugin, preparing your iOS code, running the conversion, resolving unmapped APIs, and testing—you can produce a solid Android app foundation. Remember that while the tool automates 70-80% of the work, manual refinement is essential for robust, platform-native performance. With practice, you’ll master the conversion workflow and ensure your app reaches the majority of mobile users worldwide.