Swift, Add multiple markers on GMSMapView

I am new to Google map and i want to add multiple markers to GMSMapView and infoWindow.

My code below

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for Prop: Property in properties

{

var latStr = Prop.lat as NSString

var latDbl : Double = Double(latStr.intValue)

var langStr = Prop.lang as NSString

var langDbl : Double = Double(langStr.intValue)

position = CLLocationCoordinate2DMake(latDbl, langDbl)

london = GMSMarker(position: position)

london.flat = true

london.map = googleMapView

}

Can some one please let me know..What i am doing wronge or someone can edit my code and show me the correct way?

Thanks in advance for the help!