lifecycle.kt

// create observer
class ActivityLifecycleObserver: LifecycleObserver {

    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
    fun lifecycleResume() {
        Log.d(MainActivity.TAG, "$this on resume")
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    fun lifecyclePause() {
        Log.d(MainActivity.TAG, "$this on pause")
    }


    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
    fun lifecycleDestroy() {
        Log.d(MainActivity.TAG, "$this on destroy")
    }
}

// add it to the activity/fragmanet
lifecycle.addObserver(ActivityLifecycleObserver())


if (lifeCycle.currentState.isAtLeast(Lifecycle.State.STARTED)) {
    //...
}