RxOkHttp.kt

import java.io.IOException
import okhttp3.Call
import okhttp3.Callback
import okhttp3.Response
import rx.Single

fun Call.toSingle(): Single<Response> =
    Single.create { subscriber ->
        enqueue(object : Callback {
            override fun onResponse(call: Call, response: Response) {
                if (!subscriber.isUnsubscribed) {
                    subscriber.onSuccess(response)
                }
            }
            override fun onFailure(call: Call, e: IOException) {
                if (!subscriber.isUnsubscribed) {
                    subscriber.onError(e)
                }
            }
        })
    }