领域迁移未称为 [英] Realm migration not called

问题描述

我已经向领域对象添加了一个值(我已经向WeekReport对象添加了动态var inspectorName =")，并且我正在尝试迁移领域数据库以包含该值.我正在尝试像这样在func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil)中调用迁移块:

I've added a value to a realm object (I've added dynamic var inspectorName = "" to the WeekReport object), and I'm trying to migrate the realm database to contain that value. I'm trying to call the migration block in func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) like this:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    print("HERE")
    Realm.Configuration.defaultConfiguration = Realm.Configuration(
        schemaVersion: 1,
        migrationBlock: { migration, oldSchemaVersion in
            if (oldSchemaVersion < 1) {
                migration.enumerateObjects(ofType: WeekReport.className()) { oldObject, newObject in
                    newObject!["inspectorName"] = ""
                }
            }
    })

    return true
}

但是似乎我的错误发生之前没有调用didFinishLaunchingWithOptions.

But it seems that didFinishLaunchingWithOptions isn't called before my error happens.

在多视图控制器中，我有let realm = try! Realm().在运行应用程序时，Xcode在这里中断:

In multiple view controller i have let realm = try! Realm(). Here Xcode breaks when I run the app:

"由于以下错误，需要迁移: -已添加属性'WeekReport.inspectorName'."UserInfo = {NSLocalizedDescription =由于以下错误，需要迁移: -已添加属性"WeekReport.inspectorName".错误代码= 10}:文件/Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-800.0.63/src/swift/

"Migration is required due to the following errors: - Property 'WeekReport.inspectorName' has been added." UserInfo={NSLocalizedDescription=Migration is required due to the following errors: - Property 'WeekReport.inspectorName' has been added., Error Code=10}: file /Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-800.0.63/src/swift/

为什么不调用迁移blick?从未打印过"HERE" ...

How come the migration blick isn't called? "HERE" is never printed...

我应该在视图控制器中以不同的方式定义领域吗?

Should I define realm in a different way in my view controllers?

推荐答案

如果在视图控制器中将let realm = try! Realm()作为实例变量编写，则会在Storyboard中的application: didFinishLaunchingWithOptions之前调用它.要解决此问题，可以改用lazy var realm = try! Realm(). lazy推迟创建实例变量，直到访问该变量为止.

If you write let realm = try! Realm() in a view controller as an instance variable, it will be called before application: didFinishLaunchingWithOptions from Storyboard. To resolve this, you can use lazy var realm = try! Realm() instead. lazy defers creating an instance variable until the variable is accessed.

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