Wait until a fragment is created and execute a lambda with the fragment as an argument.

waitUntilCreated.kt

import android.arch.lifecycle.Lifecycle
import android.arch.lifecycle.LifecycleObserver
import android.arch.lifecycle.LifecycleOwner
import android.arch.lifecycle.OnLifecycleEvent
import android.support.v4.app.Fragment

inline fun <reified T : Fragment>Fragment.waitUntilCreated(crossinline callback: (T) -> Unit) {
    val activationObject: LifecycleOwner = this
    object : LifecycleObserver {
        init {
            activationObject.lifecycle.addObserver(this)
        }

        @OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
        fun onCreate() {

            check(activationObject is T) {
                "The activation object and the generic type differs."
            }
            callback(activationObject as T)
        }
    }
}

Sample usage

fragment.waitUntilCreated<DecksFragment> { 
    println("Do whatever you want with ${it}")
}