Boilerplate for bound services (may become a part of http://github.com/Miha-x64/Flawless) later

BoundService.kt

package net.aquadc.flawless.service

import android.app.Service
import android.content.Context
import android.content.Intent
import android.content.ServiceConnection
import android.os.Binder
import android.os.IBinder

/**
 * An Android service which provides a plain, Android-independent service.
 * https://gist.github.com/Miha-x64/e792377d5a408442226923da9085f4b1
 */
abstract class BoundService<T> : Service() {

    /**
     * Actual service which should be returned to Activity.
     */
    protected abstract val actual: T

    /**
     * A binder which will expose our [actual] service, when invoked as a function.
     */
    private val binder = object : Binder(), () -> Any? {
        override fun invoke(): Any? = actual
    }

    final override fun onBind(intent: Intent?): IBinder? =
            binder

}

/**
 * Reified shortcut for [Context.bindService] with an empty [Intent] and [Context.BIND_AUTO_CREATE] flag.
 */
inline fun <reified T : BoundService<*>> Context.bindService(connection: ServiceConnection) {
    check(bindService(Intent(this, T::class.java), connection, Context.BIND_AUTO_CREATE))
}

/**
 * @return actual service provided by a [BoundService] instance
 */
@Suppress("UNCHECKED_CAST") // I don't mind, really
fun <T> IBinder.getActual(): T =
        (this as () -> Any?)() as T

sample.kt

class SomeServiceHost : BoundService<SomeService>() {

    override val actual = SomeService()

    // and do whatever you need

}

class SomeUi : Activity or Fragment, ServiceConnection {
  
      override fun onStart() {
        super.onStart()
        bindService<SomeServiceHost>(this)
    }

    override fun onStop() {
        unbindService(this)
        super.onStop()
    }


    override fun onServiceConnected(name: ComponentName, service: IBinder) {
        service.getActual<SomeService>().doWhateverYouNeed()
    }

    override fun onServiceDisconnected(name: ComponentName) {
        doCleanUp()
    }
  
}