ios - Attempting to change MKAnnotation color within my code? -

so have set mkannotations in mapview , it's working want to. experiment further , try change colors of pins, efficient way implement within following code:

override func viewdidappear(animated: bool) { var annotationquery = pfquery(classname: "post") currentloc = pfgeopoint(location: mapviewlocationmanager.location) //annotationquery.wherekey("location", neargeopoint: currentloc, withinmiles: 10) annotationquery.wherekeyexists("location") annotationquery.findobjectsinbackgroundwithblock {     (points, error) -> void in     if error == nil {         // find succeeded.         println("successful query annotations")         // found objects          let myposts = points as! [pfobject]          post in myposts {             let point = post["location"] as! pfgeopoint             let annotation = mkpointannotation()             annotation.coordinate = cllocationcoordinate2dmake(point.latitude, point.longitude)             annotation.title = post["title"] as! string!             annotation.subtitle = post["username"] as! string!              func mapview(amapview: mkmapview!,                     viewforannotation annotation: mkannotation!) -> mkannotationview! {                          let reuseid = "pin"                         var pinview = amapview.dequeuereusableannotationviewwithidentifier(reuseid) as? mkpinannotationview                              println("pinview nil")                             pinview = mkpinannotationview(annotation: annotation, reuseidentifier: reuseid)                             pinview!.canshowcallout = true                             pinview!.animatesdrop = true                             pinview!.pincolor = .green                         return pinview                 }               self.mapview.addannotation(annotation)         }      } else {         // log details of failure         println("error: \(error)")     } } 

i can't seem tackle on own though seem's simple enough. confused viewforannotation method, gather seems need use it, nothing i'm trying working.