swift - NSCoding for a non-compliant object (MKMapItem) -

trying save mkmapitem part of custom class.

 import uikit  import mapkit   class place: nsobject, nscoding {   var mapitem : mkmapitem!  var type : category!   init(mapitem: mkmapitem, type: category) {    self.mapitem = mapitem    self.type = type   }  // mark: nscoding     required init?(coder decoder: nscoder) {         mapitem = decoder.decodeobject(forkey: "mapitem") as! mkmapitem?        type = decoder.decodeobject(forkey: "type") as! category?     }      func encode(with coder: nscoder) {        coder.encode(mapitem, forkey: "mapitem")       coder.encode(type, forkey: "type")     }   } 

but won't work because mkmapitem not nscoding-compliant (compiler doesn't complain though). understand how encode custom classes, can't figure out how object defined ios.

i know there 1 answer out there objective-c on this, swift solution. thanks.

ps have tried subclass mkmapitem , provide "new" initializers, though take considerable code changes elsewhere. leads "cannot assign property: 'placemark' get-only property". both 'placemark' , 'iscurrentlocation' get-only.

import uikit import mapkit  class newmapitem: mkmapitem {       required init(placemark: mkplacemark, iscurrentlocation:bool, name: string,         phonenumber: string, url: url, timezone: timezone) {     self.placemark = placemark  //compiler complains "get-only"     self.iscurrentlocation = iscurrentlocation  //compiler complains "get-only"     self.name = name     self.phonenumber  = phonenumber     self.url = url     self.timezone = timezone  }  // mark: nscoding  init?(coder decoder: nscoder) {      placemark = (decoder.decodeobject(forkey: "placemark") as! mkplacemark?)! //compiler complains "get-only"     iscurrentlocation = decoder.decodebool(forkey: "iscurrentlocation")  //compiler complains "get-only"     name = decoder.decodeobject(forkey: "name") as? string     phonenumber = decoder.decodeobject(forkey: "phonenumber") as? string     url = decoder.decodeobject(forkey: "url") as! url?     timezone = decoder.decodeobject(forkey: "timezone") as! timezone? }  func encode(with coder: nscoder) {      coder.encode(placemark, forkey: "placemark")     coder.encode(iscurrentlocation, forkey: "iscurrentlocation")     coder.encode(name, forkey: "name")     coder.encode(phonenumber, forkey: "phonenumber")     coder.encode(url, forkey: "url")     coder.encode(timezone, forkey: "timezone") } } 

i have figured out.

break down mapitem in "func encode(with coder: nscoder)" , build again in "init?(coder decoder: nscoder)"

i did take advantage of mkmapitem initializer placemark.

   mkmapitem(placemark: placemark!) 

here working class:

import uikit import mapkit  class place: nsobject, nscoding {    var mapitem : mkmapitem!   var type : category!    init(mapitem: mkmapitem, type: category) {     self.mapitem = mapitem     self.type = type   }  // mark: nscoding     required init?(coder decoder: nscoder) {      //liberate properties of mapitem , rebuild     // let iscurrentlocation = decoder.decodeobject(forkey: "iscurrentlocation") as! bool //don't need set       let name = decoder.decodeobject(forkey: "name") as! string?       let phonenumber = decoder.decodeobject(forkey: "phonenumber") as! string?       let url = decoder.decodeobject(forkey: "url") as! url?       let timezone = decoder.decodeobject(forkey: "timezone") as! timezone?       let placemark = decoder.decodeobject(forkey: "placemark") as! mkplacemark?       self.mapitem = mkmapitem(placemark: placemark!)      self.mapitem.name = name      self.mapitem.url = url      self.mapitem.phonenumber = phonenumber      //self.mapitem.iscurrentlocation = iscurrentlocation //don't need this. set      self.mapitem.timezone = timezone       type = decoder.decodeobject(forkey: "type") as! category?     }     func encode(with coder: nscoder) {      let placemark = mapitem.placemark      let name = mapitem.name      let phonenumber  = mapitem.phonenumber      let url = mapitem.url      let timezone = mapitem.timezone       coder.encode(name, forkey: "name")      coder.encode(phonenumber,forkey: "phonenumber")      coder.encode(url, forkey: "url")      coder.encode(timezone, forkey: "timezone")      coder.encode(type, forkey: "type")      coder.encode(placemark, forkey: "placemark")     }  }