### Checking your development environment with `kdoctor`
**Before opening the project in Android Studio**, use [`kdoctor`](https://github.com/Kotlin/kdoctor) to ensure your development environment is configured correctly. Install `kdoctor` via [`brew`](https://brew.sh/):
```
brew install kdoctor
```
Then, run `kdoctor` from your terminal. If everything is set up correctly, you should see valid output. Otherwise, `kdoctor` will provide you which parts of your setup still need configuration:
```
Environment diagnose (to see all details, use -v option):
[✓] Operation System
[✓] Java
[✓] Android Studio
[✓] Xcode
[✓] Cocoapods
Conclusion:
✓ Your system is ready for Kotlin Multiplatform Mobile Development!
```
## Opening the project
Use Android Studio to open the project. Make sure you have the [Kotlin Multiplatform Mobile plugin](https://plugins.jetbrains.com/plugin/14936-kotlin-multiplatform-mobile) installed.
## Examining the project structure
Switch to the Project View to see all files and targets belonging to the project.
Your Compose Multiplatform project includes three modules:
### `shared`
This Kotlin module that contains the logic common for both Android and iOS applications – the code you share between platforms.
**This is also where you will write your Compose Multiplatform code**.
The shared root `@Composable` function for your app lives in `shared/src/commonMain/kotlin/App.kt`.
`shared` uses Gradle as the build system. You can add dependencies and change settings in `shared/build.gradle.kts`. The shared module builds into an Android library and an iOS framework.
### `androidApp`
This Kotlin module that builds into an Android application. It uses Gradle as the build system. The androidApp module depends on and uses the shared module as a regular Android library.
### `iosApp`
This is the Xcode project that builds into an iOS application. It depends on and uses the shared module as a CocoaPods dependency.
## Running your application
## Android
To run your application on an Android emulator:
- Create an [Android virtual device](https://developer.android.com/studio/run/managing-avds#createavd).
We suggest going through the "Hello, World" steps of creating and deploying a sample project in Xcode to a simulator and/or your physical device.
A video tutorial for setting up Xcode and running your first "Hello, World" application is available in [this Standford CS193P lecture recording](https://youtu.be/bqu6BquVi2M?start=716&end=1399).
### Running on an iOS simulator
Once you have configured your environment correctly, you will be able to select which iOS simulator to run your application in Android Studio on by modifying the `iosApp` run configuration.
Select "Run" | "Edit Configurations..." and navigate to the "iOS Application" | "iosApp" run configuration. In the "Execution target" drop-down, select your target device.
- Run the `iosApp` run configuration from Android Studio (it will fail)
- Open the `iosApp/iosApp.xcworkspace` in Xcode
- Select `iosApp` in the menu on the left side
- Navigate to "Signing & Capabilities"
- Select your Personal Team in the "Team" dropdown. If you haven't set up your team, use the "Add account..." option and follow the steps inside Xcode.
The common entry point for your Compose Multiplatform app is located in `shared/src/commonMain/kotlin/App.kt`. Here, you will see the code that is responsible for rendering the "Hello, World" button. If you make changes here, you will see them reflected on both Android and iOS:
```kotlin
@Composable
internal fun App() {
MaterialTheme {
var text by remember { mutableStateOf("Hello, World!") }
Button(onClick = {
text = "Hello, ${getPlatformName()}"
}) {
Text(text)
}
}
}
```
Update the shared code by adding a text field that will update the name displayed on the button:
```kotlin
@Composable
internal fun App() {
MaterialTheme {
var text by remember { mutableStateOf("Hello, World!") }
This template contains a `iosApp/Configuration/Config.xcconfig` configuration file that allows you to configure most basic properties without having to move to Xcode. It contains:
-`APP_NAME` - target executable and application bundle name
Note: To configure the `APP_NAME` setting, open `Config.xcconfig` in any text editor *before opening* the project in Android Studio, and set the desired name.
If you need to change this setting after you open the project in Android Studio, please do the following:
- close the project in Android Studio
- run `./cleanup.sh` in your terminal
- change the setting
- open the project in Android Studio again
For configuring advanced settings, you can use Xcode. Open the `iosApp/iosApp.xcworkspace` in Xcode after opening the project in Android Studio, and use Xcode to make your changes.
