So Many New Kotlin & Compose Features 😱 - Mobile Dev News September 2025

Summary

In this video, the host shares exciting updates for mobile developers, especially within the Kotlin and Android ecosystem. Key highlights include the release of Kotlin 2.2.0, featuring new language features like context parameters, context-sensitive resolution, and multi-dollar string interpolation. Additionally, JetBrains' future focus on Kotlin Multiplatform promises improvements in build speed, iOS compatibility, and web target use cases. Android Studio introduces Gemini AI agent mode, while Jetpack Compose 1.9 offers new features such as a drop shadow modifier and enhanced text input handling. Lastly, the host promotes a free online workshop on Kotlin Multiplatform, set for September 13th.

Takeaways

• 😀 A free online workshop about Kotlin Multiplatform and Compose is happening on September 13th, offering a technical deep dive with tips and under-the-hood insights.
• 😀 Kotlin 2.2.0 introduces context parameters, allowing more efficient passing and accessing of objects within specific contexts, improving code readability and reducing boilerplate.
• 😀 Kotlin 2.2.0 also includes context-sensitive resolution in preview, allowing simplified 'when' expressions by referencing enum values directly, similar to Swift's syntax.
• 😀 The new @All annotation in Kotlin 2.2.0 allows you to apply an annotation to all parts of a property (param, getter, setter, etc.), streamlining code.
• 😀 Nested type aliases are now possible in Kotlin, letting developers define type aliases within classes for more localized and organized type management.
• 😀 Stable language features in Kotlin 2.2.0 include guard conditions for smarter type casting, non-local breaks and continues in inline lambdas, and multi-dollar string interpolation for cleaner formatting.
• 😀 JetBrains is focusing on improving the Kotlin Multiplatform (KMP) experience, with plans for faster build speeds, enhanced Kotlin-to-Swift export, and more web target use cases.
• 😀 JetBrains is also working on providing more Jetpack libraries for Kotlin Multiplatform, including Navigation 3 and Paging 3, alongside improvements to text input on iOS for a more native experience.
• 😀 Kotlin Multiplatform now generates documentation for Kotlin equivalents of Objective-C classes, improving the developer experience when working with iOS and Android in KMP.
• 😀 Android Studio's new feature drop patch 1.2 includes the Gemini AI agent, which allows developers to interact with AI inside their IDE for coding assistance and composable UI updates.
• 😀 Jetpack Compose 1.9 introduces new modifiers such as drop shadow, inner shadow, visibility change handling, and prefetch options for lazy columns, along with improvements in text input formatting for better usability.

Q & A

What is the focus of the workshop being hosted on September 13th?

The workshop focuses on a deep dive into Kotlin and Kotlin Multiplatform, specifically covering technical details, tips, and how the technologies work under the hood. It's free to attend as long as spots are available.

What new feature has been introduced in Kotlin 2.2.0 that is currently in preview?

Kotlin 2.2.0 introduces 'context parameters' in preview. This feature allows you to define parameters that can only be used in specific contexts, making the code cleaner and more efficient by reducing the need to pass around objects.

How do context parameters improve Kotlin code?

Context parameters allow you to restrict the usage of certain parameters to specific classes or contexts, enabling you to write more concise and type-safe code. For example, you can ensure that a function can only be called within a specific ViewModel context.

What is the difference between 'context-sensitive resolution' and 'context parameters' in Kotlin?

'Context-sensitive resolution' allows you to reference enum values directly in a 'when' expression without needing to repeat the class name. This is different from context parameters, which define context-specific arguments for functions.

What are 'nested type aliases' in Kotlin 2.2.0 and why are they useful?

Nested type aliases allow you to define type aliases inside classes, making them accessible only within that class. This is useful for organizing complex types and avoiding global declarations that can clutter the namespace.

What is the purpose of the 'all annotation' feature in Kotlin 2.2.0?

The 'all annotation' feature allows you to apply a single annotation to all parts of a property, such as the field, getter, and setter, which simplifies the process of applying annotations across multiple property components.

How does Kotlin 2.2.0 handle non-local breaks and continue statements?

Kotlin now allows 'break' and 'continue' statements in inline lambdas within loops, enabling more flexible control flow within higher-order functions, which was previously not possible.

What is 'multi-string interpolation' in Kotlin 2.2.0, and why is it helpful?

Multi-string interpolation allows you to use multiple dollar signs ('$') in strings to differentiate between interpolation and literal dollar signs. This is especially useful when dealing with strings that need to include literal dollar signs, like in financial or schema data.

What are JetBrains' priorities for Kotlin Multiplatform in the coming months?

JetBrains' priorities for Kotlin Multiplatform include improving the developer experience by enhancing build speeds, improving Kotlin-to-Swift export features, and expanding use cases for web targets like Kotlin WebAssembly.

What new features are introduced in Jetpack Compose 1.9 for Android?

Jetpack Compose 1.9 introduces several new features, including a proper drop shadow modifier, visibility change modifiers, lazy column prefetch options, and improved text input formatting, all aimed at making UI development more flexible and efficient.