A better way

CustomArrayAdapter.kt

class CustomArrayAdapter(context: Context,
                         @LayoutRes private val layoutResource: Int,
                         @IdRes private val textViewResourceId: Int = 0,
                         private val values: List<ModelDisplayName>) : ArrayAdapter<ModelDisplayName>(context, layoutResource, values) {

    override fun getItem(position: Int): ModelDisplayName = values[position]

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        val view = createViewFromResource(convertView, parent, layoutResource)

        return bindData(getItem(position), view)
    }

    override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup): View {
        val view = createViewFromResource(convertView, parent, android.R.layout.simple_spinner_dropdown_item)

        return bindData(getItem(position), view)
    }

    private fun createViewFromResource(convertView: View?, parent: ViewGroup, layoutResource: Int): TextView {
        val context = parent.context
        val view = convertView ?: LayoutInflater.from(context).inflate(layoutResource, parent, false)
        return try {
            if (textViewResourceId == 0) view as TextView
            else {
                view.findViewById(textViewResourceId) ?:
                        throw RuntimeException("Failed to find view with ID " +
                                "${context.resources.getResourceName(textViewResourceId)} in item layout")
            }
        } catch (ex: ClassCastException){
            Log.e("CustomArrayAdapter", "You must supply a resource ID for a TextView")
            throw IllegalStateException(
                    "ArrayAdapter requires the resource ID to be a TextView", ex)
        }
    }

    private fun bindData(value: ModelDisplayName, view: TextView): TextView {
        view.text = value.displayName
        return view
    }
}