how to create a dotted polyline in Google Maps with swift 2.0

Question

I've tried this question that has some relevant objC code, but my swift2.0 version only produces dashed (and not dotted) lines. This is my code:

let path = // ... I define my path here
let route = GMSPolyline(path: path)
route.strokeWidth = 4.0
let styles = [GMSStrokeStyle.solidColor(UIColor(red: 0.945, green: 0.392, blue: 0.278, alpha: 1.0)), GMSStrokeStyle.solidColor(UIColor.clearColor())]
let lengths = [15,15]
route.spans = GMSStyleSpans(route.path!, styles, lengths, GMSLengthKind(rawValue: 1)!);
route.map = m_map_view