swift - Save map annotation using UserDefaults -

i have been searching relentlessly solution , left no choice except rely on expertise here on stackoverflow. working on saving map annotation if app closes , have been using userdefault save annotation.

this objective c code found , tried converting swift , think there error it. not sure. place code @ viewdidload()

this save annotation

    var pinnedannotation: cllocationcoordinate2d = (parkedcarannotation?.coordinate)!     var coordinatedata: nsdata = nsdata(bytesnocopy: pinnedannotation, length: sizeof(pinnedannotation), freewhendone: false)     userdefaults.standard.set(coordinatedata, forkey: pinnedannotation)     userdefaults.standard.synchronize() 

and needed load annotation when app open.

i dont know if viewdidload right place put. put in mapview function of updatinglocation

edited: added code further clarification of have done needed corrected

override func viewdidload() {     super.viewdidload()     mapview.delegate = self mkmapviewdelegate     checklocationauthorizationstatus()     tabbar.delegate = self      if userdefaults.standard.object(forkey: "pinnedannotation") != nil {         let annotation = mkpointannotation()          self.mapview.addannotation(annotation)     }  }  func locationmanager(_ manager: cllocationmanager, didupdatelocations locations: [cllocation]) {     let pinnedannotation: cllocationcoordinate2d = (parkedcarannotation?.coordinate)!     let locationdata = ["latitude": parkedcarannotation?.coordinate.latitude, "longitude": parkedcarannotation?.coordinate.longitude]     userdefaults.standard.set(locationdata, forkey: "pinnedannotation")     userdefaults.standard.synchronize()     print("saving data ",  userdefaults.standard.set(locationdata, forkey: "pinnedannotation"))  }   func tabbar(_ tabbar: uitabbar, didselect item: uitabbaritem) {     if(item.tag == 0){         if mapview.annotations.count == 1{             mapview.addannotation(parkedcarannotation!)          } else {             mapview.removeannotation(mapview.annotations as! mkannotation)         }     }   extension viewcontroller: mkmapviewdelegate { func mapview(_ mapview: mkmapview, viewfor annotation: mkannotation) -> mkannotationview? {     if let annotation = annotation as? parkingspot{         let identifier = "pin"         var view: mkpinannotationview         view = mkpinannotationview(annotation: annotation, reuseidentifier: identifier)         view.canshowcallout = true         view.animatesdrop = true         view.pintintcolor = uicolor.orange         view.calloutoffset = cgpoint(x: -8, y: -3)         view.rightcalloutaccessoryview = uibutton.init(type:.detaildisclosure) uiview         return view     } else {         return nil     } }  extension viewcontroller: cllocationmanagerdelegate{ func mapview(_ mapview: mkmapview, didupdate userlocation: mkuserlocation) {     centermaponlocation(location: cllocation(latitude: userlocation.coordinate.latitude, longitude: userlocation.coordinate.longitude))     let locationservicecoordinate = locationservice.instance.locationmanager.location!.coordinate      parkedcarannotation = parkingspot(title: "my parking spot", locationname: "find way car location", coordinate: cllocationcoordinate2d(latitude: locationservicecoordinate.latitude, longitude: locationservicecoordinate.longitude))   } 

}

i'm not entirely sure you're asking...

for starters when you're saving data userdefaults key needs string, believe you'll need save data in userdefaults dictionary

let locationdata = ["lat": parkedcarannotation?.coordinate?.latitude, "long": parkedcarannotation?.coordinate.longitude]   userdefaults.standard.set(locationdata, forkey: "pinned_annotation") 

and retrieve data call

if let annotationdata = userdefaults.standard.object(forkey: "pinned_annotation") as? dictionary {     guard let lat = annotationdata["lat"], let long = annotationdata["long"] else { return }     let coordinate = cllocationcoordinate2d(latitude: lat, longitude: long) } 

now should able set annotation coordinate