How to wait and execute code after AsyncHttpClient() Done?

Question

I want to take data from API using AsyncHttpClient(), after that, I show the data to recycle view. but when trying to debug my code is run show the data to recycle view which is no data because not yet finish setData using AsyncHttpClient(). my question is how to run setData recycle view adapter after my setLeague is finish getting data? Sorry, I am a newbie and I put my code below. Please help, I already try using async-await but doesn't work.

This is my ViewModel Class

val footballLeagueList = MutableLiveData<ArrayList<league>>()

internal fun setLeague(){
    val client = AsyncHttpClient()
    val client2 = AsyncHttpClient()
    val listItems = ArrayList<league>()
    val leagueListUrl = "https://www.thesportsdb.com/api/v1/json/1/all_leagues.php"
    val leagueDetailUrl = "https://www.thesportsdb.com/api/v1/json/1/lookupleague.php?id="

    client.get(leagueListUrl, object : AsyncHttpResponseHandler(){
        override fun onSuccess(
            statusCode: Int,
            headers: Array<out Header>?,
            responseBody: ByteArray?
        ) {
            try{
                val result = String(responseBody!!)
                val responseObject = JSONObject(result)

                for(i in 0 until 10){
                    val list = responseObject.getJSONArray("leagues")
                    val leagues = list.getJSONObject(i)
                    val leaguesItems = league()
                    val detailUrl = leagueDetailUrl + leagues.getString("idLeague")
                    leaguesItems.id = leagues.getString("id")
                    leaguesItems.name = leagues.getString("strLeague")
                    leaguesItems.badgeUrl = leagues.getString( "https://www.thesportsdb.com/images/media/league/badge/dqo6r91549878326.png")
                    listItems.add(leaguesItems)
                }
                footballLeagueList.postValue(listItems)
            }catch (e: Exception){
                Log.d("Exception", e.message.toString())
            }
        }

        override fun onFailure(
            statusCode: Int,
            headers: Array<out Header>?,
            responseBody: ByteArray?,
            error: Throwable?
        ) {
            Log.d("Failed", "On Failure")
        }

    })

}

internal fun getLeague(): LiveData<ArrayList<league>> {
    return footballLeagueList
}

And this is my MainActivity

class MainActivity : AppCompatActivity() {

    private lateinit var mainViewModel: MainViewModel
    private lateinit var adapterLeague: leagueAdapter

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        adapterLeague = leagueAdapter()
        adapterLeague.notifyDataSetChanged()
        verticalLayout {
            lparams(matchParent, matchParent)
            recyclerView {
                layoutManager = GridLayoutManager(context, 2)
                adapter = adapterLeague
            }
        }

        mainViewModel = ViewModelProvider(this, ViewModelProvider.NewInstanceFactory())
            .get(MainViewModel::class.java)

        mainViewModel.setLeague()

        mainViewModel.getLeague().observe(this, Observer { leaguesItems ->
            if(leaguesItems != null){
                adapterLeague.setData(leaguesItems)
           }
        })
    }
}