XCode - Setting a Button as leftCalloutAccessoryView in MKAnnotationView

Question

I'm attempting to set a button with the text "Button" as the left callout accessory view. Here is what I have so far

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if let annotation = annotation as? LocationObjects{
        if let view = mapView.dequeueReusableAnnotationView(withIdentifier: annotation.identifier){
            return view
        }else{
            let view = MKAnnotationView(annotation: annotation, reuseIdentifier: annotation.identifier)
            view.isEnabled = true
            view.canShowCallout = true
            view.image = annotationPin

            let test = UIButton(type: .system)
            test.setTitle("Button", for: .normal)

            view.leftCalloutAccessoryView = test
            return view
        }
    }
    return nil
}

It throws an error after

test.setTitle("Button", for: .normal)

But will not throw an error if I remove that line and set

let test = UIButton(type: .system)

to

let test = UIButton(type: .detailDisclosure)

How can I set the button to have text instead of an image or default system icon?

Thanks!