我正在尝试我的第一个轻量级CoreData迁移.我阅读了两本关于轻量级迁移的指南.两者都将代码添加到CoreDataStack类,修改NSPersistentStoreCoordinator等变量并添加：
let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true,NSInferMappingModelAutomaticallyOption: true]
我的问题是我有一个功能完善的应用程序使用CoreData,但我没有那个类或类似的东西.我的问题是,为什么这些项目假设我有这个课程,我可以在没有它的情况下实现轻量级迁移吗？如果没有,我该如何添加？
更多信息,如果需要回答
九月份,我使用CoreData构建了一个应用程序.这是我第一次使用CoreData,我遵循了Ray Wenderlich指南.它工作得很好,我完成了应用程序,现在它在商店里.现在我想开始对应用程序进行一些更改,其中涉及新的CoreData属性和一些新实体.我读过我需要设置一个新的模型版本.
我找到了一个Ray Wenderlich guide,但它使用了我没有的CoreDataStack.swift文件：
令人沮丧的是,我使用他们的指南设置了CoreData,但它没有包含该文件！然后我去做迁移,他们认为我有它.
我去寻找另一个轻量级的迁移方法,发现这个alternative,它也引用了我从未在我的CoreData中构建的代码：
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
// The persistent store coordinator for the application. This implementation creates and return a coordinator,having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
// Create the coordinator and store
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("MyLog.sqlite")
var error: NSError? = nil
var failureReason = "There was an error creating or loading the application's saved data."
if coordinator!.addPersistentStoreWithType(NSsqliteStoreType,configuration: nil,URL: url,options: nil,error: &error) == nil {
coordinator = nil
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
dict[NSLocalizedFailureReasonErrorKey] = failureReason
dict[NSUnderlyingErrorKey] = error
error = NSError(domain: "YOUR_ERROR_DOMAIN",code: 9999,userInfo: dict)
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application,although it may be useful during development.
NSLog("Unresolved error \(error),\(error!.userInfo)")
abort()
}
所以我已经阅读了指南并理解了90％的教程.我只需要有人看看原始的CoreData教程并告诉我在哪里,如果我没有CoreData类,我会添加轻量级代码,例如：
let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true,NSInferMappingModelAutomaticallyOption: true]
