Post about this Gist is on Medium: https://medium.com/@uludagcan/observable-livedata-rx-bind-extensions-4f2188a53ad1

ReactiveBindExtensions.kt

import android.graphics.Bitmap
import android.graphics.drawable.Drawable
import android.view.View
import android.widget.ImageView
import android.widget.TextView
import androidx.lifecycle.LifecycleOwner
import androidx.lifecycle.LiveData
import androidx.lifecycle.Observer
import com.jakewharton.rxrelay2.BehaviorRelay
import io.reactivex.disposables.CompositeDisposable
import io.reactivex.rxkotlin.addTo

fun <T> LiveData<T>.bindText(lifecycleOwner: LifecycleOwner, textView: TextView?) {
    this.observe(lifecycleOwner, Observer { textView?.text = it.toString() })
}

fun LiveData<Bitmap>.bindBitmap(lifecycleOwner: LifecycleOwner, imageView: ImageView?) {
    this.observe(lifecycleOwner, Observer { imageView?.setImageBitmap(it) })
}

fun LiveData<Drawable>.bindDrawable(lifecycleOwner: LifecycleOwner, imageView: ImageView?) {
    this.observe(lifecycleOwner, Observer { imageView?.setImageDrawable(value) })
}

fun LiveData<Boolean>.bindVisibility(lifecycleOwner: LifecycleOwner, view: View?) {
    this.observe(
        lifecycleOwner,
        Observer { value ->
            view?.visibility = if (value) View.VISIBLE else View.GONE
        })
}

fun <T> BehaviorRelay<T>.bindText(textView: TextView?, bag: CompositeDisposable) {
    this.subscribe { textView?.text = it.toString() }?.addTo(bag)
}

fun BehaviorRelay<Boolean>.bindVisibility(view: View?, bag: CompositeDisposable) {
    this.subscribe { view?.isSelected = it }?.addTo(bag)
}