CoroutineScope and Job integration with Lifecycle for Android. Meant to be used for your coroutines in lifecycle aware components. Ongoing PR: https://github.com/Kotlin/kotlinx.coroutines/pull/655

LifecycleCoroutines.kt

import android.arch.lifecycle.GenericLifecycleObserver
import android.arch.lifecycle.Lifecycle
import android.arch.lifecycle.Lifecycle.Event.ON_DESTROY
import android.arch.lifecycle.LifecycleOwner
import kotlinx.coroutines.experimental.CoroutineScope
import kotlinx.coroutines.experimental.Dispatchers
import kotlinx.coroutines.experimental.Job
import kotlinx.coroutines.experimental.android.Main

fun Lifecycle.createJob(cancelEvent: Lifecycle.Event = ON_DESTROY): Job {
    if(cancelEvent in forbiddenCancelEvents) {
        throw UnsupportedOperationException("$cancelEvent is forbidden for createJob(…).")
    }
    return Job().also { job ->
        if (currentState == Lifecycle.State.DESTROYED) job.cancel()
        else addObserver(object : GenericLifecycleObserver {
            override fun onStateChanged(source: LifecycleOwner?, event: Lifecycle.Event) {
                if (event == cancelEvent) {
                    removeObserver(this)
                    job.cancel()
                }
            }
        })
    }
}

private val forbiddenCancelEvents = arrayOf(
        Lifecycle.Event.ON_ANY,
        Lifecycle.Event.ON_CREATE,
        Lifecycle.Event.ON_START,
        Lifecycle.Event.ON_RESUME
)
private val lifecycleJobs = mutableMapOf<Lifecycle, Job>()

val Lifecycle.job: Job
    get() = lifecycleJobs[this] ?: createJob().also {
        if (it.isActive) {
            lifecycleJobs[this] = it
            it.invokeOnCompletion { _ -> lifecycleJobs -= this }
        }
    }
private val lifecycleCoroutineScopes = mutableMapOf<Lifecycle, CoroutineScope>()

val Lifecycle.coroutineScope: CoroutineScope
    get() = lifecycleCoroutineScopes[this] ?: job.let { job ->
        val newScope = CoroutineScope(job + Dispatchers.Main)
        if (job.isActive) {
            lifecycleCoroutineScopes[this] = newScope
            job.invokeOnCompletion { _ -> lifecycleCoroutineScopes -= this }
        }
        newScope
    }

inline val LifecycleOwner.coroutineScope get() = lifecycle.coroutineScope

fun Lifecycle.createScope(cancelEvent: Lifecycle.Event): CoroutineScope {
    return CoroutineScope(createJob(cancelEvent) + Dispatchers.Main)
}

LifecycleStateAwait.kt

import android.arch.lifecycle.GenericLifecycleObserver
import android.arch.lifecycle.Lifecycle
import android.arch.lifecycle.LifecycleOwner
import kotlinx.coroutines.experimental.suspendCancellableCoroutine

suspend fun Lifecycle.awaitState(state: Lifecycle.State) {
    if (currentState == state) return // Fast path
    suspendCancellableCoroutine<Unit> { c ->
         if (currentState == Lifecycle.State.DESTROYED) { // Fast path to cancellation
            c.cancel()
            return@suspendCancellableCoroutine
        }
        val observer = object : GenericLifecycleObserver {
            override fun onStateChanged(source: LifecycleOwner?, event: Lifecycle.Event) {
                if (currentState == state) {
                    removeObserver(this)
                    c.resume(Unit)
                } else if (currentState == Lifecycle.State.DESTROYED) {
                    c.cancel()
                }
            }
        }
        addObserver(observer)
        c.invokeOnCancellation { removeObserver(observer) }
    }
}