Expand "Getting Started" README

README.md

@@ -2,28 +2,91 @@
 [![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 # [Compose Multiplatform](https://github.com/JetBrains/compose-multiplatform) Mobile Application
 
-Use this template to start developing your own Compose Multiplatform application targeting Android and iOS (experimental).
+Use this template to start developing your own Compose Multiplatform application targeting Android and iOS (Alpha).
+
+## Setting up your development environment
+
+Your Compose Multiplatform application targeting Android and iOS is a Kotlin Multiplatform project.
+Let's make sure you have set up your environment for mobile development with Kotlin Multiplatform.
+
+> **Warning**
+> Writing and running iOS-specific code for a simulated or real device requires macOS. This is an Apple limitation.
+
+To work with this template, you will need:
+- A machine running a recent version of macOS
+- [Xcode](https://developer.apple.com/xcode/)
+- [Android Studio](https://developer.android.com/studio)
+- [Kotlin Multiplatform Mobile plugin](https://plugins.jetbrains.com/plugin/14936-kotlin-multiplatform-mobile)
+- [CocoaPods](https://kotlinlang.org/docs/native-cocoapods.html)
+
+### 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.
+
+![](readme_images/open_project_view.png)
+
+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 on Android, use the `androidApp` run configuration in [Android Studio](https://developer.android.com/studio)
+To run your application on an Android emulator:
-or use Gradle:
+
+- Create an [Android virtual device](https://developer.android.com/studio/run/managing-avds#createavd).
+- Select the `androidApp` run configuration.
+- Select your target device and press **Run**.
+
+![](readme_images/run_on_android.png)
+
+<details>
+  <summary>Using Gradle</summary>
 
 `./gradlew installDebug` - install Android application on an Android device (on a real device or on an emulator)
 
+</details>
+
 ## iOS
 
-Make sure you have set up your environment for mobile development with Kotlin Multiplatform. A detailed guide on how to set up your environment is available in the [Kotlin Multiplatform documentation](https://kotlinlang.org/docs/multiplatform-mobile-setup.html).
-
-To work with the iOS target you need:
-- A machine running a recent version of macOS
-- [Xcode](https://developer.apple.com/xcode/) (to setup the environment)
-- [Android Studio](https://developer.android.com/studio)
-- [Kotlin Multiplatform Mobile plugin](https://plugins.jetbrains.com/plugin/14936-kotlin-multiplatform-mobile) (to work with all supported targets, including iOS)
-- [CocoaPods](https://kotlinlang.org/docs/native-cocoapods.html)
-
-**Before opening the project in Android Studio**, make sure that your environment is set up for iOS and Kotlin Multiplatform development.
-Use [`kdoctor`](https://github.com/Kotlin/kdoctor) to ensure your development environment is configured correctly.
-
 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).
 
@@ -33,28 +96,33 @@ Once you have configured your environment correctly, you will be able to select
 
 Select "Run" | "Edit Configurations..." and navigate to the "iOS Application" | "iosApp" run configuration. In the "Execution target" drop-down, select your target device.
 
+![](readme_images/edit_run_config.png)
+
+![](readme_images/target_device.png)
+
+Press the "Run" button to run your Compose Multiplatform app on the iOS simulator.
+
+![](readme_images/hello_world_ios.png)
+
 ### Running on a real iOS device
 
 Running your Compose Multiplatform application on a physical device can be done for free. You need:
 - an [Apple ID](https://support.apple.com/en-us/HT204316)
 - the registered iOS device in Xcode
 
-#### Running with a free Personal Team
+Before you continue, make sure that you can successfully run a plain "Hello, World" application from Xcode on your physical device.
 
-If you use a free Personal Team for signing applications to run on a real device, you'll have to find your team ID.
+To run the application, set the `TEAM_ID` associated with your Apple ID in `iosApp/Configuration/Config.xcconfig`.
 
-The easiest way is to refer to your "Hello, World" project that you created while setting up your development environment. Use your terminal to navigate to the folder where you have created the Xcode project (`.xcodeproj`) and run the following command:
+#### Finding your Team ID
-
+Use `kdoctor --team-ids` to find and set your Team ID. This will list all Team IDs currently configured on your system, for example:
-```bash
+```
-grep -r "DEVELOPMENT_TEAM"
+3ABC246XYZ (Max Sample)
+ZABCW6SXYZ (SampleTech Inc.)
 ```
 
-In your multiplatform project, navigate to `iosApp/Configuration/Config.xcconfig` and set the `TEAM_ID` to the value you've gotten from the previous command.
-
 <details>
-<summary>Alternative approaches</summary>
+<summary>Alternative way of finding your Team ID</summary>
-
-To see your local team ID, you try running `security find-certificate -c "Apple Development" -p | openssl x509 -noout -text | grep --color 'OU=\w\w\w\w*'` in your terminal.
 
 If you're running into trouble with the method described above, you can try this alternative method.
 - Run the `iosApp` run configuration from Android Studio (it will fail)
@@ -64,16 +132,50 @@ If you're running into trouble with the method described above, you can try this
 - 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.
 </details>
 
-After that you can open the project in Android Studio, and it will show the registered iOS device in the `iosApp`
+Set this Team ID in `iosApp/Configuration/Config.xcconfig` in the `TEAM_ID` field.
+
+After that you can re-open the project in Android Studio, and it will show the registered iOS device in the `iosApp`
 run configuration.
 
-#### Running with a paid Team
 
-- Find your [Team ID](https://developer.apple.com/help/account/manage-your-team/locate-your-team-id/#:~:text=A%20Team%20ID%20is%20a,developer%20in%20App%20Store%20Connect.). 
+### Make your first changes
-- set this Team ID in `iosApp/Configuration/Config.xcconfig` in the `TEAM_ID` field
 
-After that you can open the project in Android Studio, and it will show the registered iOS device in the `iosApp` 
+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:
-run configuration.
+```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!") }
+        Column {
+            Button(onClick = {
+                text = "Hello, ${getPlatformName()}"
+            }) {
+                Text(text)
+            }
+            TextField(text, onValueChange = { text = it })
+        }
+    }
+}
+```
+
+![](readme_images/text_field_added.png)
 
 ### Configuring the iOS application