Question

我一直在尝试使用Xcode8为我的Core Data架构执行轻量级迁移，并遇到一些奇怪的问题。我第一次在更新后加载商店，并在选项字典中将NSMigratePersistentStoresAutomaticallyOption和NSInferMappingModelAutomaticallyOption标志设置为YES，我遇到了这个错误：

2016-10-01 09:59:17.307862 CJournal[1162:549816] loadLocalStoreIntoPSC using store = file:///private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/ContactsJournal.sqlite
2016-10-01 09:59:18.373568 CJournal[1162:549816] [error] error: Failed to delete support directory for store: /private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/.ContactsJournal.sqlite.migrationdestination_41b5a6b5c6e848c462a8480cd24caef3
2016-10-01 09:59:18.656164 CJournal[1162:549816] [error] error: CoreData: error: (migration) migration failed with error (null)
2016-10-01 09:59:18.664001 CJournal[1162:549816] [error] error: -addPersistentStoreWithType:SQLite configuration:(null) URL:file:///private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/ContactsJournal.sqlite options:{
    NSInferMappingModelAutomaticallyOption = 1;
    NSMigratePersistentStoresAutomaticallyOption = 1;
} ... returned error Error Domain=NSSQLiteErrorDomain Code=8 "(null)" UserInfo={NSFilePath=/private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/ContactsJournal.sqlite, Source database Path=/private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/.ContactsJournal.sqlite.migrationdestination_41b5a6b5c6e848c462a8480cd24caef3, reason=Failed to replace destination database} with userInfo dictionary {
    NSFilePath = "/private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/ContactsJournal.sqlite";
    "Source database Path" = "/private/var/mobile/Containers/Shared/AppGroup/04521C25-2FE6-4CFD-ACB5-70550B63499E/.ContactsJournal.sqlite.migrationdestination_41b5a6b5c6e848c462a8480cd24caef3";
    reason = "Failed to replace destination database";
}

在iOS10模拟器和iOS10设备上都会发生这种情况。奇怪的是第二次运行我运行应用程序并尝试迁移，它运行正常，没有任何错误！

这是我用来添加商店的代码：

NSMutableDictionary *options = [NSMutableDictionary dictionaryWithObjectsAndKeys:@YES, NSMigratePersistentStoresAutomaticallyOption, @YES, NSInferMappingModelAutomaticallyOption, nil];

NSPersistentStore *newStore = [self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:localStoreURL options:options error:&error];

我还尝试在＆＃34;启动时传递的参数＆＃34;中使用-com.apple.CoreData.MigrationDebug 1标志。但它并没有产生任何可能有用的输出。

知道可能出现什么问题，或者如果由于某些验证问题导致迁移失败，如何调试？

Answer 1

我发现了问题...在轻量级迁移之前，我正在对现有数据库进行备份，因此我创建了一个NSPersistentStoreCoordinator（与通常的堆栈分开）并向其添加了persistentStore没有任何轻量级迁移选项。这显然会锁定商店文件，即使在备份过程完成后，也会阻止主Core Data堆栈persistentStoreCoordinator上的迁移。解决方法是从备份persistentStoreCoordinator中删除persistentStore。这可以确保迁移正常，addPersistentStoreWithType此时不会抛出错误。

Xcode8和Core Data自动轻量级迁移

1 个答案: