xcode - Post expiration time with Swift in iOS 8? -

users can post pin on map @ location, once post pin set on map forever user post. set time expiration on these posts, after 24 hours post wiped , gone. i'm not sure if parse thing or if part of xcode?

here add pins:

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!                 let annotationsubtitleuser = post["username"] as! string!                  let formatter = nsdateformatter()                 formatter.datestyle = nsdateformatterstyle.shortstyle                 formatter.timestyle = .shortstyle                 let datestring = formatter.stringfromdate(post.createdat!)                  annotation.subtitle = "user: \(annotationsubtitleuser)  time: \(datestring)"                  self.mapview.addannotation(annotation)             }          } else {             // log details of failure             println("error: \(error)")         }     } 

thank in advance!