无法在 Swift 中进行领域迁移

Question

我有一个提醒对象，我刚刚修改了它。这是原始版本：

class Reminder: Object {
   @objc dynamic var title = ""
   @objc dynamic var parents = ""
   @objc dynamic var lists = "All"
   @objc dynamic var labels = "All"
   @objc dynamic var priority = 
   @objc dynamic var notes = ""
   @objc dynamic var reminderType = .none
}

这是新版本：

class Reminder: Object {
    @objc dynamic var title = ""
    @objc dynamic var parents = ""
    @objc dynamic var lists = "All"
    @objc dynamic var dueDate = 0.0
    @objc dynamic var reminderDate = 0.0
    @objc dynamic var reminderLocation = ""
    @objc dynamic var labels = "All"
    @objc dynamic var priority = 1
    @objc dynamic var notes = ""
}

我已经实现了 AppDelegate 的迁移块didFinishLaunchingWithOptions 方法。这里是：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    ///Realm migration
    let config = Realm.Configuration(
        // Set the new schema version. This must be greater than the previously used
        // version (if you've never set a schema version before, the version is 0).
        schemaVersion: 2,

        // Set the block which will be called automatically when opening a Realm with
        // a schema version lower than the one set above
        migrationBlock: { migration, oldSchemaVersion in

            if oldSchemaVersion < 2 {

            }
    }
    )
    Realm.Configuration.defaultConfiguration = config
    let _ = try! Realm()

    return true
}

根据文档，我认为应该是功能迁移。但是，在编译应用程序时出现以下错误：

Fatal error: 'try!' expression unexpectedly raised an error: Error Domain=io.realm Code=10 "Migration is required due to the following errors:
- Property 'Reminder.reminderLocation' has been added.
- Property 'Reminder.reminderDate' has been added.
- Property 'Reminder.dueDate' has been added.
- Property 'Reminder.reminderType' has been removed."

我应该在迁移块中进行哪些更改？

提前谢谢你

Answer 1

当存储的数据与代码中的模型不匹配时，将引发此异常。

您不需要在迁移块中执行任何操作，但是您需要通过更新 Realm.Configuration.schemaVersion 的值来触发迁移，例如：

schemaVersion: 3,