Compose Multiplatform in Action: Taking It Easy, An Introduction to CMP

Hello everyone!
This series will focus on Compose Multiplatform in Action: Developing Cross-platform Apps from Scratch with Kotlin
I’ll concentrate on developing cross-platform apps for Android and iOS
In the final days, I’ll also share my findings and insights from my research

Let’s first get a basic understanding of Compose Multiplatform and Kotlin Multiplatform

The term Multiplatform itself is simply Multi + platform
As the name suggests, it means supporting multiple platforms

According to the JetBrains official website,
Compose Multiplatform allows developers to use Kotlin’s Compose declarative UI
to develop applications
Currently supported platforms include iOS, Android, Desktop, and Web

Some people also refer to it as KMM (Kotlin Mobile Multiplatform)
or CMP (Compose Multiplatform), KMP (Kotlin Multiplatform)
In this series, I’ll use CMP to refer to Compose Multiplatform
to reduce repetition throughout the articles
I hope you can get used to this abbreviation!

Both aim to simplify cross-platform project development
reducing the time spent writing and maintaining the same code for different platforms

You can use Gradle configurations
along with shared source code development to reduce development time
such as developing cross-platform code through commonMain
Compose UI is developed in this layer

Here are the main differences:

KMP requires using native platform code to create the UI layout for target apps
For example:
Android uses xml to implement layouts
or more recently, Android has evolved to using Compose for UI implementation

iOS uses SwiftUI for implementation

CMP extends the KMP concept
It similarly allows writing shared code
and now supports using Compose to create multi-platform UI

As shown below, I can create multi-platform UI using just Compose

Of course, this UI is created using Material Design 3
Some might be concerned that it doesn’t match iOS design guidelines

However, my past practical experience has taught me
that when working on projects
most UI designs
are primarily based on iOS screens

Therefore, apart from platform-specific components
careful customization can create screens that look almost identical to iOS

So this aspect depends on each person’s use case
and whether they care about these differences XD

Finally
In these thirty days, I’ll share the following topics

• Understanding CMP basic environment configuration
• Mastering CMP basic creation methods, project configuration, and simulator configuration
• Understanding CMP program entry points
• Using Material Design 3 Theme in CMP
• Concrete methods for implementing UI with Compose
• Using expect and actual to implement cross-platform code
• Understanding how to use Koin for DI injection in CMP
• How to handle Android context requirements in CMP development?
• Implementing DataStore for local persistent storage in CMP
• Implementing local database using SqlDelight in CMP
• Implementing local database using Room in CMP and solving the [KSP2] Annotation value is missing in nested annotations issue
• Importing CocoaPods and using iOS frameworks in CMP projects
• Using cinterop and iOS frameworks in CMP projects
• …and more

Starting tomorrow
I’ll begin writing notes to help everyone better understand Compose Multiplatform

Additionally, CMP is constantly being updated
Based on articles published by Google

It’s likely that more support
will be gradually added to CMP
which is something to look forward to

(Image source: Google Blog)

Since CMP is relatively new
we might encounter various situations
and there isn’t as much information available online
so if you encounter any issues, we can discuss them and learn from each other