6 August 2026

Kotlin Multiplatform Setup

Kotlin Multiplatform Setup: Install the necessary tool

Tool	Purpose	Verify Installation	If Not Installed
Android Studio	Main IDE for Android and KMP development.	Open Android Studio or check if it appears in the Applications folder (macOS).	Download and install Android Studio from the official website.
Xcode (macOS only)	Required to build and run iOS applications on a simulator or a physical device. Skip this if you’re developing on Windows or Linux.	`bash\nxcodebuild -version\n`	Install Xcode from the Mac App Store, launch it once, accept the license, and allow it to install additional components.
OpenJDK (Java)	Required by Gradle, Kotlin Multiplatform tooling, and other command-line tools.	`bash\njava --version\n`	If the command is not found, install OpenJDK using Homebrew and configure `JAVA_HOME`.
Kotlin Multiplatform Plugin	Adds Kotlin Multiplatform support to Android Studio.	Android Studio → Settings → Plugins → Search for Kotlin Multiplatform.	Install the plugin and restart Android Studio.
Kotlin Plugin	Provides Kotlin language support. It is installed with Android Studio by default.	Android Studio → Settings → Plugins → Verify that Kotlin is enabled.	Normally no action is required. If disabled or missing, update or reinstall Android Studio.

Verify Your Environment

Once all the required tools are installed, verify your environment using KDoctor.

KDoctor helps you verify whether your Kotlin Multiplatform environment is configured correctly.

Note: KDoctor works only on macOS. If you’re using Windows or Linux, you can skip this step.

Step 1: Check if Homebrew is Installed

Run the following command in the terminal:

brew --version

If you see an output similar to:

Homebrew 6.0.12

you can proceed to the next step.

If you get an error such as:

brew: command not found

install Homebrew first:

if brew not installl u can go to the to this and install it in ur Mac

https://brew.sh

/bin/bash-c"$(curl -fsSL <https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh>)"

After installation, verify it again:

brew --version

Step 2: Install KDoctor

Once Homebrew is installed, run:

brew install kdoctor

If KDoctor is already installed, you may see:

Warning: kdoctor is already installed and up-to-date.

Step 3: Verify the Environment

Run:

kdoctor

A healthy environment should report most components with a ✓ status.

Example:

[✓] Operating System
[✓] Java
[✓] Xcode
[✓] Android Studio

If KDoctor reports warnings or errors, refer to the Troubleshooting section.

Troubleshooting

Java Not Found

Error

[✖] Java not found

rishiz@Rushi-MacBook-Air ~ % kdoctor


rishiz@Rushi-MacBook-Air ~ % kdoctor
Environment diagnose (to see all details, use -v option):
[✓] Operation System
[✖] Java
  ✖ Java not found
    Get JDK from <https://www.oracle.com/java/technologies/javase-downloads.html>
[!] Android Studio
  ! Android Studio (AI-253.30387.90.2532.14935130)
    Location: /Applications/Android Studio.app
    Bundled Java: openjdk 21.0.9 2025-10-21
    Kotlin Plugin: 253.30387.90.2532.14935130-AS
    Kotlin Multiplatform Mobile Plugin: not installed
    Install Kotlin Multiplatform Mobile plugin - <https://plugins.jetbrains.com/plugin/14936-kotlin-multiplatform-mobile>
[✓] Xcode
[!] CocoaPods
  ! CocoaPods configuration is not required, but highly recommended for full-fledged development
  ✖ System ruby is currently used
    CocoaPods is not compatible with system ruby installation on Apple M1 computers.
    Please install ruby via Homebrew, rvm, rbenv or other tool and make it default
    Detailed information: <https://stackoverflow.com/questions/64901180/how-to-run-cocoapods-on-apple-silicon-m1/66556339#66556339>
  ✖ cocoapods not found
    Get cocoapods from <https://guides.cocoapods.org/using/getting-started.html#installation>

Conclusion:
  ✖ KDoctor has diagnosed one or more problems while checking your environment.
    Please check the output for problem description and possible solutions.

[✖] Java
Java not found

[!] CocoaPods
System ruby is currently used
cocoapods not found

[✓] Xcode

At first it appeared that Java was the main issue preventing iOS development.

Most off the time if Mac OS update, most likely cause is that the update removed or invalidated the JDK registration. Android Studio still has its own bundled JDK, but your terminal no longer has a system Java.

Solution

Android Studio Already Included Java

KDoctor detected:

Bundled Java: openjdk 21.0.9

This means Android Studio already ships with its own JDK.

However, the terminal environment did not have a system Java installation, which caused KDoctor to fail the Java check.

Install OpenJDK 21

Installed Java:

brew install openjdk@21

Configured:

export PATH="/opt/homebrew/opt/openjdk@21/bin:$PATH"
export JAVA_HOME="/opt/homebrew/opt/openjdk@21"

Verification:

java -version

Result:

openjdk 21

Java issue resolved.

No compatible Apple Simulator Runtime found

No compatible Apple Simulator Runtime found
for used SDK: iphonesimulator26.5

This suggested a mismatch between:

Installed SDK
Installed Simulator Runtime

Simulator Investigation

Checked available runtimes:

xcrun simctl list runtimes

Result:

iOS 26.3
iOS 26.5

Both runtimes were installed.

Device Verification

Checked simulator devices:

xcrun simctl list devices

Result:

iPhone 17 Pro
iPhone 17 Pro Max
iPhone 17e
iPhone Air
Multiple iPads

All simulators were available and properly registered.

Root Cause

The issue was not actually Java.

Most likely:

Xcode had recently updated.
Simulator runtimes were still syncing/registering.
Diagnostic tools reported stale information.
Opening Simulator and refreshing Xcode components resolved the issue.
Android Studio refreshed the available iOS targets.

Afterward, all simulators appeared correctly.

Final Environment Status

[✓] Operating System
[✓] Java
[✓] Android SDK
[✓] Xcode
[✓] Gradle Project

Environment is fully operational.

Remaining Warnings

macOS 26.5+ is not yet supported
Xcode 26.5+ is not yet supported

These are compatibility warnings from tooling.

They mean:

The diagnostic tool has not officially validated the newest macOS/Xcode version yet.

They do NOT mean:

KMP or iOS development is broken.

Since:

KDoctor passes
Simulator launches
iOS devices are visible
Gradle project validates
KMP project runs

these warnings can be safely ignored.

Notes About Java

Android Studio already contains:

openjdk 21.0.9

For Android-only development, a separate system JDK is often unnecessary.

However, some command-line tools such as:

Gradle
KDoctor
KMP CLI tools

expect a system Java installation.

Therefore keeping OpenJDK 21 installed is generally recommended unless disk space is extremely limited.

launch the iOS Simulator on your Intel Mac:

Method 1 — Using Spotlight (Fastest)

Press:

Command (⌘) + Space

Type:

Simulator

Open:

iOS Simulator

Method 2 — From Xcode

Open Xcode

Then go to:

Xcode → Open Developer Tool → Simulator

Method 3 — Using Terminal

Run:

open-a Simulator

If Simulator is not installed

You need Xcode installed.

You can install it from:

Mac App Store – Xcode

After installing Xcode once:

Open Xcode
Accept license
Let it install additional components

Then Simulator will work.

To run your app in Simulator

Inside Xcode:

Open your iOS project
At top toolbar choose a device like:
- iPhone 16
- iPhone SE
- iPad
Press:

Command (⌘) + R

or click ▶ Run.

Useful Simulator shortcuts

Action	Shortcut
Home button	`Command + Shift + H`
Screenshot	`Command + S`
Rotate device	`Command + Left/Right Arrow`
Toggle dark mode	`Features → Appearance`
Shake device	`Device → Shake`

For KMP / Compose Multiplatform projects

If you are running from Android Studio or IntelliJ:

First start Simulator manually:

open-a Simulator

Then run:

iosApp

or select the iOS run configuration from the IDE.

Changing the Default iOS Simulator

By default, running the following command:

open-a Simulator

launches the Simulator application and restores the last used simulator device (for example, iPhone 16).

If you want to change the simulator that opens by default:

Launch the Simulator:open-a Simulator

Right-click the Simulator icon in the macOS Dock.
Select the desired device from the menu:Device → iPhone 17 (or any other simulator you want to use).
Close the Simulator.

The next time you run:

open-a Simulator

the Simulator will open with the last selected device (e.g., iPhone 17).

Launch a Specific Simulator from the Terminal

Instead of relying on the last used device, you can boot a specific simulator directly.

Example (using the simulator UUID):

xcrun simctl boot B5D25DB3-0455-4E33-AED7-D11BD602664D
open-a Simulator

Or shut down all simulators first and then boot the required one:

xcrun simctl shutdown all
xcrun simctl boot B5D25DB3-0455-4E33-AED7-D11BD602664D
open-a Simulator

This ensures that the specified simulator (e.g., iPhone 17) is launched instead of the previously used device

on click on arrow u will get the devices .

Kotlin Multiplatform Setup

Table of Contents

Verify Your Environment

Step 1: Check if Homebrew is Installed

Step 2: Install KDoctor

Step 3: Verify the Environment

Troubleshooting

Java Not Found

Error

Solution

Android Studio Already Included Java

Install OpenJDK 21

No compatible Apple Simulator Runtime found

Simulator Investigation

Device Verification

Root Cause

Final Environment Status

Remaining Warnings

Notes About Java

launch the iOS Simulator on your Intel Mac:

Method 1 — Using Spotlight (Fastest)

Method 2 — From Xcode

Method 3 — Using Terminal

If Simulator is not installed

To run your app in Simulator

Useful Simulator shortcuts

For KMP / Compose Multiplatform projects

Changing the Default iOS Simulator

Launch a Specific Simulator from the Terminal

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Table of Contents

Verify Your Environment

Step 1: Check if Homebrew is Installed

Step 2: Install KDoctor

Step 3: Verify the Environment

Troubleshooting

Java Not Found

Error

Solution

Android Studio Already Included Java

Install OpenJDK 21

No compatible Apple Simulator Runtime found

Simulator Investigation

Device Verification

Root Cause

Final Environment Status

Remaining Warnings

Notes About Java

launch the iOS Simulator on your Intel Mac:

Method 1 — Using Spotlight (Fastest)

Method 2 — From Xcode

Method 3 — Using Terminal

If Simulator is not installed

To run your app in Simulator

Useful Simulator shortcuts

For KMP / Compose Multiplatform projects

Changing the Default iOS Simulator

Launch a Specific Simulator from the Terminal

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