Laravel Collective上多个选择的选定值

Question

I've got a string value from a controller which is:

$pickedValues = "1,2";

So what I'm trying to do is set the multiple selected values on the view, here is the select code that I have right now:

{{Form::select("selection[]", $data, (isset($pickedValues)) ? array($pickedValues) : '',
        [
            "class"    => "multiple-select",
            "multiple",
        ])
}}

That problem that I'm getting right now that it is not displaying the selected options, but if I put the values manually like array(1,2) it works. I've tried setting it as array((int)$pickedValues) but it only displays the value 1.