无法从 iCloud 迁移永久存储

Posted 2023-03-05

【中文标题】无法从 iCloud 迁移永久存储

【英文标题】：Not Able to Migrate Persistent Store Away from iCloud

【发布时间】：2015-11-16 01:50:27

【问题描述】：

我正在尝试从我的应用程序中的 NSPersistentStore 中删除 iCloud 同步功能。迁移不会返回任何错误，但是，启用 iCloud 的持久存储中的数据会在迁移后消失。

以下是我的相关代码：

-(void)setUpCoreDataStackWithICloud

//Set up the model and context.
    self.model = [NSManagedObjectModel mergedModelFromBundles:nil];
    self.context = [[NSManagedObjectContext alloc]init];
    [self.context setMergePolicy:NSMergeByPropertyObjectTrumpMergePolicy];

    if ([self isiCloudEnabledOnThisDevice]==YES) 
        [self setUpiCloud];

        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
        [defaults setValue:[NSNumber numberWithBool:YES] forKey:@"lastLaunchOfAppiCloudWasEnabled"];

    else self.psc = [self persistentStoreCoordinatorForUserWithoutiCloudEnabled];

    [self.context setPersistentStoreCoordinator:self.psc];

    -(NSPersistentStoreCoordinator*)persistentStoreCoordinatorForUserThatAlreadyMigratedToiCloud

    NSLog(@"persistentStoreCoordinatorForUserThatAlreadyMigratedToiCloud called");
    NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc]initWithManagedObjectModel:self.model];

    NSError *error = nil;

    NSPersistentStore *store = [psc addPersistentStoreWithType:NSSQLiteStoreType
                                                 configuration:nil
                                                           URL:[self newStoreURL]
                                                       options:[self iCloudStoreOptions]
                                                         error:&error];
    if (!store) 
        NSLog(@"failed to add store with error %@",  [error localizedDescription]);
    else NSLog(@"successfully added store for user that has already migrated to iCloud");


    NSDictionary *migrateOptions = @ NSPersistentStoreRemoveUbiquitousMetadataOption : @YES,
                           NSMigratePersistentStoresAutomaticallyOption : @YES,
                           NSInferMappingModelAutomaticallyOption : @YES;

    NSError *migrationError = nil;

    NSPersistentStore *migratedStore = [psc migratePersistentStore:store toURL:[self testNewestStoreURL] options:migrateOptions withType:NSSQLiteStoreType error:&migrationError];

    if (migrationError) 
        NSLog(@"Migration from iCloud enabled persistent store was unsuccessful. %@", migrationError.localizedDescription);
    else NSLog(@"The migration from the iCloud enabled persistent store was successful");

    NSLog(@"The migrated store is %@", migratedStore);

    return psc;
 

-(NSURL*)testNewestStoreURL
NSString *path = [self itemArchivePathWithAppendedString:@"test.data"];
NSURL *storeURL = [NSURL fileURLWithPath:path];
return storeURL;


-(NSURL*)newStoreURL

            NSString *path = [self itemArchivePathWithAppendedString:@"cloudstore.data"];
            NSURL *storeURL = [NSURL fileURLWithPath:path];
            return storeURL;
        

【参考方案1】：

它不起作用的原因是因为我也在使用映射模型进行架构迁移。根据文档，iCloud 不支持此功能。即使我试图摆脱 iCloud，当涉及到架构迁移时，它也不允许访问数据。