This project is named after the Kaluga, the world’s biggest freshwater fish, which is found in the icy Amur river.

Kaluga’s main goal is to provide access to common features used in cross-platform mobile app development, separated into modules such as architecture (MVVM), location, permissions, bluetooth etc.

To reach this goal it uses Kotlin, specifically Kotlin Multiplatform which allows running Kotlin code not just on JVM+Android, but also iOS/iPadOS, amongst others (inndeed some kaluga modules also work for Kotlin.js and/or JVM standalone).

Where appropriate coroutines and Flow are used in the API. This enables developers to use cold streams for a modern and efficient design.

While Kaluga modules can be used individually, together they form a comprehensive approach to cross-platform development with shared native code and native UIs, including SwiftUI and Compose.

Short examples

With Kaluga it is possible to create cross-platform functionality in a few lines of code, that would normally take many lines of code even on just one platform.

Below are some examples, using a commonMain source-set:

Scanning for nearby devices with Bluetooth LE:

// will auto request permissions and try to enable bluetooth
BluetoothBuilder().create().devices().collect {
i("discovered device: $it") // log found device
}

Showing a spinner while doing some work:

suspend fun doWork(hudBuilder: HUD.Builder) {
hudBuilder.presentDuring { // shows spinner while code in this block is running
// simulate doing work
delay(1000)
}
}

in this case, since HUD is a UI component the builder needs to be configured on the platform side:

val builder = HUD.Builder() // same for iOS and Android
// ...
builder.subscribe(activity) // this needs be done in the Android source-set to bind the HUD to the lifecycle of the Activity
// ...
builder.unsubscribe(activity) // when the Activity is stopped

However Kaluga’s architecture module offers a cross-platform LifecycleViewModel class (which extends androidx.lifecycle.ViewModel on Android) that will automatically bind the builder to its lifecycle:

// this can just be in the commonMain source
class HudViewModel(private val hudBuilder: HUD.Builder): BaseLifecycleViewModel(hudBuilder) {

suspend fun doWork() =
hudBuilder.presentDuring {
delay(1000)
}
}

More examples

Kaluga contains an example project that is used to test the developed modules.

Using Kaluga

For starting a new project based on Kaluga see the kaluga-starter repo, which shows how to do this step by step.

Kaluga is available on Maven Central. For example the Kaluga Alerts can be imported like this:

repositories {
mavenCentral()
}
dependencies {
implementation("com.splendo.kaluga:alerts:$kalugaVersion")
}

You can also use the SNAPSHOT version based on the latest in the develop branch:

repositories {
maven("https://s01.oss.sonatype.org/content/repositories/snapshots/")
}
dependencies {
implementation("com.splendo.kaluga:alerts:$kalugaDevelopVersion-SNAPSHOT")
}

To use kaluga with SwiftUI and/or Combine we have a repo with Sourcery templates to generate some Swift code to help get you started.

Available Modules

Module	Usage	Artifact Name
alerts	Used for Showing Alert Dialogs	com.splendo.kaluga:alerts
architecture	MVVM architecture	com.splendo.kaluga:architecture
architecture-compose	Compose extensions for architecture	com.splendo.kaluga:architecture-compose
base	Core components of Kaluga. Contains threading, flowables and localization features	com.splendo.kaluga:base
beacons	Tracking the availability of Beacons using the Eddystone protocol	com.splendo.kaluga:beacons
bluetooth	Scanning for and communicating with BLE devices	com.splendo.kaluga:bluetooth
date-time	Contains multiplatform classes to work with date and time	com.splendo.kaluga:date-time
date-timepicker	Used for showing a Date or Time Picker	com.splendo.kaluga:date-time-picker
hud	Used for showing a Loading indicator HUD	com.splendo.kaluga:hud
keyboard	Used for showing and hiding the keyboard	com.splendo.kaluga:keyboard
keyboard-compose	Compose extensions for keyboard	com.splendo.kaluga:keyboard-compose
links	Used for decoding url into an object	com.splendo.kaluga:links
location	Provides the User’ geolocation	com.splendo.kaluga:location
logging	Shared console logging	com.splendo.kaluga:logging
media	Playing audio/video	com.splendo.kaluga:media
base-permissions	Managing permissions, used in conjunction with modules below	com.splendo.kaluga:base-permissions
bluetooth-permissions	Managing bluetooth permissions	com.splendo.kaluga:bluetooth-permissions
calendar-permissions	Managing calendar permissions	com.splendo.kaluga:calendar-permissions
camera-permissions	Managing camera permissions	com.splendo.kaluga:camera-permissions
contacts-permissions	Managing contacts permissions	com.splendo.kaluga:contacts-permissions
location-permissions	Managing location permissions	com.splendo.kaluga:location-permissions
microphone-permissions	Managing microphone permissions	com.splendo.kaluga:microphone-permissions
notifications-permissions	Managing notifications permissions	com.splendo.kaluga:notifications-permissions
storage-permissions	Managing storage permissions	com.splendo.kaluga:storage-permissions
resources	Provides shared Strings, Images, Colors and Fonts	com.splendo.kaluga:resources
resources-compose	Compose extensions for resources	com.splendo.kaluga:resources-compose
resources-databinding	Data Binding extensions for resources	com.splendo.kaluga:resources-databinding
review	Used for requesting the user to review the app	com.splendo.kaluga:review
scientific	Scientific units and conversions	com.splendo.kaluga:scientific
service	Used for adding services to Kaluga	com.splendo.kaluga:service
system	System APIs such as network, audio, battery	com.splendo.kaluga:system
test-utils	Enables easier testing of Kaluga components	com.splendo.kaluga:test-utils
test-utils-base	Enables easier testing of Kaluga components	com.splendo.kaluga:test-utils-base
test-utils-alerts	Enables easier testing of Alerts module	com.splendo.kaluga:test-utils-alerts
test-utils-architecture	Enables easier testing of Architecture module	com.splendo.kaluga:test-utils-architecture
test-utils-bluetooth	Enables easier testing of Bluetooth module	com.splendo.kaluga:test-utils-bluetooth
test-utils-date-time-picker	Enables easier testing of Date Time Picker module	com.splendo.kaluga:test-utils-date-time-picker
test-utils-hud	Enables easier testing of HUD module	com.splendo.kaluga:test-utils-hud
test-utils-keyboard	Enables easier testing of Keyboard module	com.splendo.kaluga:test-utils-keyboard
test-utils-koin	Enables easier testing with Koin	com.splendo:kaluga.test-utils-koin
test-utils-location	Enables easier testing of Location module	com.splendo.kaluga:test-utils-location
test-utils-permissions	Enables easier testing of Permissions modules	com.splendo.kaluga:test-utils-permissions
test-utils-resources	Enables easier testing of Resources module	com.splendo.kaluga:test-utils-resources
test-utils-service	Enables easier testing of Service module	com.splendo.kaluga:test-utils-service
test-utils-system	Enables easier testing of System module	com.splendo.kaluga:test-utils-system

Friends of kaluga

Of course not every possible functionality is provided by kaluga. However, this is often because other good multiplatform libraries that work nicely with kaluga already exist. These use similar patterns such as coroutines and Flow, and include the following:

Project	Usage
kotlin-firebase-sdk	wraps most of the Firebase SDK APIs
multiplatform-settings	store key/value data
SQLDelight	access SQLite (and other SQL database)

Kaluga also uses some multiplatform libraries itself, so our thanks to:

Project	Usage
Napier	powers the logging module
Koin	dependency injection

Developing Kaluga

see DEVELOP.