ios - Send Location of User in Background Swift -

i building app user clicks button , 60mins (or amount of time) keep track of them uploading location server. using 'did update locations' function send users location firebase in real-time.

func locationmanager(manager: cllocationmanager, didupdatelocations locations: [cllocation]) {  } 

this system works spams server sending location of user server once every second.

this data , need send users location server once every 10-30 seconds.

what can send users location once every 10-30 seconds?

class viewcontroller: uiviewcontroller, cllocationmanagerdelegate {     private var locman = cllocationmanager()     private var starttime: date? //an instance variable, used previous location time.  func locationmanager(_ manager: cllocationmanager, didupdatelocations locations: [cllocation]) {      guard let loc = locations.last else { return }      let time = loc.timestamp      guard let starttime = starttime else {         self.starttime = time // saving time of first location, use compare later second location time.         return //returning function, @ moment don't have second location.      }      let elapsed = time.timeintervalsince(starttime) // calculating time interval between first , second (previously saved) locations timestamps.      if elapsed > 30 { //if time interval more 30 seconds         print("upload updated location server")         updateuser(location: loc) //user function uploads user location or coordinate server.          starttime = time //changing our timestamp of previous location timestamp of location uploaded.      } }