領域遷移：更新多個對象和備用策略？

Question

我不明白如何遷移多個對象。例如，如何在對象Settings和Person中引入字符串「標識符」？

func configureRealm(){ 

     Realm.Configuration.defaultConfiguration = Realm.Configuration(
      schemaVersion: 1, 
      migrationBlock: { migration, oldSchemaVersion in 

       migration.enumerate(Settings.className()) { oldObject, newObject in 

        if oldSchemaVersion < 1 { 
         newObject!["identifier"] = NSUUID().UUIDString 
        } 
       } 
     }) 
    } 

是否有可能引入一個通用的回退策略：當遷移失敗時，模型應該重置？

Answer 1

在遷移塊，你可以再補充一個電話Migration().enumerate(_:_:)爲Person對象：

func configureRealm(){ 

     Realm.Configuration.defaultConfiguration = Realm.Configuration(
      schemaVersion: 1, 
      migrationBlock: { migration, oldSchemaVersion in 

       migration.enumerate(Settings.className()) { oldObject, newObject in 
        if oldSchemaVersion < 1 { 
         newObject!["identifier"] = NSUUID().UUIDString 
        } 
       } 
       migration.enumerate(Person.className()) { oldObject, newObject in 
        if oldSchemaVersion < 1 { 
         // change whatever needs to be changed 
        } 
       } 
     }) 
    } 

或者你可以只刪除境界文件時let realm = try Realm()拋出一個錯誤：

do { 
    let realm = try Realm() 
    ... 
} catch { 
    let path = RLMRealmConfiguration.defaultRealmPath() 
    try! NSFileManager.defaultManager().removeItemAtPath(path) 
}