ios - Flag Annotation overlap and interchange to each other -

i facing problem show multiple annotation on mkmapview. question that, have 3 type annotation as(select_starflag, simple_flag, currentlocation_flag). flag show on map there interchange position between them, when scroll map, flag overlap each other. using following code

func mapview(mapview: mkmapview!, viewforannotation annotation: mkannotation!) -> mkannotationview! { if (annotation.iskindofclass(mkuserlocation)) {         //if annotation not mkpointannotation (eg. mkuserlocation),         //return nil map view draws"blue dot" standard user location         return nil     } if (annotation.iskindofclass(mkpointannotation)){     let reuseid = "test"     var anview = mapview.dequeuereusableannotationviewwithidentifier(reuseid) mkannotationview!     if (anview == nil) {              anview =  mkannotationview(annotation: annotation, reuseidentifier: reuseid)             anview.canshowcallout = true             var data = double(annotation.coordinate.latitude)             var data1 = double(annotation.coordinate.longitude)             var flag = bool(false)             geodata in ysdatabasegeolocationarray{                  var geolocationlat = double()                 var geolocationlong = double()                 geolocationlat = double(geodata.objectatindex(0) nsnumber)                 geolocationlong = double(geodata.objectatindex(1) nsnumber)                   if data == geolocationlat && data1 == geolocationlong {                     println(geolocationlat)                     println(geolocationlong)                     flag = true                     break                 }             }            if flag {              anview.image = uiimage(named:"select_starflag")         }         else if data == double(yslatitude) && data1 == double(yslongitude){             if  ysvalueflag != false{                 anview.image = uiimage(named:"currentlocation_flag")              }else {                  anview.image = uiimage(named:"simple_flag")             }         }         else {              anview.image = uiimage(named:"simple_flag")         }     }     else {         //we re-using view, update annotation reference..         anview.canshowcallout = true         anview.annotation = annotation         }         return anview     }     return nil }