#jetpack compose

[cata-droid]

Compose Multiplatform in 2026: Sharing UI Between Android and iOS

From Shared Logic to Shared UI If you’ve been following the Kotlin Multiplatform story, you’ve probably already shared networking with Ktor in a KMP shared module and persistence with SQLDelight across platforms. The next logical question is: can you share the UI too? With Compose Multiplatform, the answer in 2026 is a confident yes. JetBrains’ Compose Multiplatform builds on top of Jetpack…

[cata-droid]

Dynamic Theme Your App with Android WallpaperColors API

What Is the WallpaperColors API? Android 8.1 (API 27) introduced the WallpaperColors API, and it remains one of the most underrated tools for building personalized Android experiences. It lets you extract the dominant, secondary, and tertiary colors from your user’s system wallpaper and apply them to your app’s theme in real time. On Android 12+ (API 31), Google took this further with Material…

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[cata-droid]

Android Keyboard Animation: WindowInsetsAnimation API for Smooth IME Transitions

Why Android Keyboard Animation Matters When your app shows a text input and the soft keyboard slides up, that moment sets the tone for user experience. A jarring jump or a laggy animation feels cheap. A smooth, synchronized transition where your content slides up in perfect sync with the IME (Input Method Editor) feels polished and intentional. The WindowInsetsAnimation API is Android’s tool for…

[withlinda13]

I had a great time using GPT-5.3 Codex to build this Android native app (in Kotlin and Jetpack Compose) for my good friend. She specifically requested a Bible app in Batak Toba and Batak Karo languages (Pustaka Si Badia), along with a daily article displayed in a webview.

GPT-5.3 Codex is really a great model, bravo OpenAI!

[44dagainagain]

Serializer for class 'Companion' is not found.

The newish type safe Navigation Compose lets you use objects instead of strings for routes. So, typically I start with something like this if there are no parameters for the route:

@Serializable private object NewTaskDestination // ... navController.navigate(NewTaskDestination)

Then I go "oh I need to add an ID to the destination to access some resource. So I change the object into a data class:

@Serializable private data class NewTaskDestination(val resourceId: Int = 0) // … navController.navigate(NewTaskDestination)

Then, if I recompile and run, I get this exception trying to navigate:

kotlinx.serialization.SerializationException: Serializer for class 'Companion' is not found. Please ensure that class is marked as '@Serializable' and that the serialization compiler plugin is applied.

This is the most unhelpful error in the history of ever I swear to God!

wtf is Companion

what does serialization have to do with a navigation problem?

You know what the solution is? Open and closed parentheses when calling navigate:

@Serializable private data class NewTaskDestination(val resourceId: Int = 0) // … navController.navigate(NewTaskDestination())

I just dftkjhodhjpdoghj I want to murder someone now. Why didn't my IDE tell me this?!

[44dagainagain]

Kotlin: WTF is this code (trailing lambdas)

I'm trying to learn Kotlin so that I can use Jetpack Compose so that I can make an Android app. Following the Android codelab, I almost immediately hit a roadblock: wtf is this code doing:

class MainActivity : ComponentActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) enableEdgeToEdge() setContent { GreetingCardTheme { Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding -> Greeting( name = "lol", modifier = Modifier.padding(innerPadding) ) } } } } }

As a C++ developer (with a little Java knowledge), some of this is bewildering. Especially:

setContent { // ... }

WTF? It looks like a function call but there's no parentheses. It looks like a scope but how is the code run? I was scratching my head: does this have something to do with the annotation (no, that's just metadata), or something to do with accessors (no, you need to spell out get() and set()), or something to do with anonymous objects (no, you need to spell out object). Then I took a look at the setContent method declaration:

public fun ComponentActivity.setContent( parent: CompositionContext? = null, content: @Composable () -> Unit )

Ok that's interesting, the first parameter has a default so it's likely optional, and the last parameter looks like a lambda. Maybe that has something to do with it? (BTW Kotlin Unit == C++ void) So I go to the Kotlin docs and, lo and behold, there it is: trailing lambdas.

According to Kotlin convention, if the last parameter of a function is a function, then a lambda expression passed as the corresponding argument can be placed outside the parentheses [...] If the lambda is the only argument in that call, the parentheses can be omitted entirely

That means that setContent is taking a lambda. That lambda also calls a function that takes a lambda, and so on. The entire UI hierarchy is just a bunch of lambdas that something (?) eventually executes... And, despite looking like a type due to PascalCase, they are actually functions (which normally use camelCase). How this all works is a question for another day.

One more mystery:

Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding -> // ... }

In C++, lambda parameters go before the curly branches. In Kotlin, lambda parameters go inside the curly brace. Here, the Scaffold() function wants a lambda that takes padding parameters.

EDIT: To their credit, the Android Developer website mentions this in one of their codelabs. However, getting to the right codelab that contains this information is (IMO) not intuitive.

[boltuix]

🚀 New Guide! Run Python in Android Apps using Jetpack Compose + Chaquopy 🐍✨ Offline translation, ML models, no server needed! 🔧📱

📖 Step-by-step tutorial here ⬇️ 👉 https://www.reddit.com/r/AndroidDevLearn/comments/1lckuuy/stepbystep_guide_to_set_up_python_with_jetpack/

#AndroidDev #JetpackCompose #Chaquopy #Python #MobileDev #AI #DevTips #Kotlin #100DaysOfCode #OpenSource

[boltuix]

Excited to share Compose M: Kotlin Multiplatform UI Library 2025 – a game-changer for building sleek, responsive Android apps with Jetpack Compose!

This Kotlin-based UI library by BoltUIX offers:

✅ 300+ pre-built screens

☀️ Dynamic light/dark mode theming

🎨 Material Design 3 compliance

📱 Cross-device support (phones, tablets, foldables)

Compose M: Kotlin Multiplatform UI Library 2025

Compose M – App Template is a Kotlin-based UI library built on Jetpack Compose, designed to fast-track the creatio