swift - Core Data: Add a column on a table -

i want add column on table new version of app, , keep filled columns. work core data, momd:

on appdelegate:

/* core data */  // mark: - core data stack  lazy var applicationdocumentsdirectory: nsurl = {     let urls = nsfilemanager.defaultmanager().urlsfordirectory(.documentdirectory, indomains: .userdomainmask)     return urls[urls.count-1] }()  lazy var managedobjectmodel: nsmanagedobjectmodel = {     let modelurl = nsbundle.mainbundle().urlforresource("solutis", withextension: "momd")!     return nsmanagedobjectmodel(contentsofurl: modelurl)! }()  lazy var persistentstorecoordinator: nspersistentstorecoordinator = {     let coordinator = nspersistentstorecoordinator(managedobjectmodel: self.managedobjectmodel)     let url = self.applicationdocumentsdirectory.urlbyappendingpathcomponent("solutis.sqlite")     var failurereason = "there error creating or loading application's saved data."     {         try coordinator.addpersistentstorewithtype(nssqlitestoretype, configuration: nil, url: url, options: nil)     } catch let error nserror {         var dict = [string: anyobject]()         dict[nslocalizeddescriptionkey] = "failed initialize application's saved data"         dict[nslocalizedfailurereasonerrorkey] = failurereason         dict[nsunderlyingerrorkey] = error         let wrappederror = nserror(domain: "your_error_domain", code: 9999, userinfo: dict)         nslog("unresolved error \(wrappederror), \(wrappederror.userinfo)")         abort()     } catch {         fatalerror()     }      return coordinator }()   lazy var managedobjectcontext: nsmanagedobjectcontext = {     let coordinator = self.persistentstorecoordinator     var managedobjectcontext = nsmanagedobjectcontext(concurrencytype: .mainqueueconcurrencytype)     managedobjectcontext.persistentstorecoordinator = coordinator     return managedobjectcontext }()  // mark: - core data saving support  func savecontext () {     if managedobjectcontext.haschanges {         {             try managedobjectcontext.save()         } catch {             let nserror = error nserror             nslog("unresolved error \(nserror), \(nserror.userinfo)")             abort()         }     } } 

so if user update app filled table, gonna keep data , have new version of table.

but how ? juste learned add model version, how retrieve old data ?