iOS：如何创建核心数据库的备份副本？以及如何导出/导入该副本？

看看这个示例应用程序,它包括进行备份,从iCloud复制备份,通过电子邮件发送备份和从电子邮件导入备份的功能.
http://ossh.com.au/design-and-technology/software-development/sample-library-style-ios-core-data-app-with-icloud-integration/

顺便说一句,如果您要在ICloud之间进行备份,那么使用migratePersistentStore API来制作/导入备份会更安全.另请注意,示例应用程序假定您没有使用WAL模式,这是iOS 7的默认模式.WAL模式使用多个文件,这些文件都需要备份或复制.

以下是展示示例应用备份和还原功能的视频的链接.

http://ossh.com.au/design-and-technology/software-development/sample-library-style-ios-core-data-app-with-icloud-integration/sample-apps-explanations/backup-files/

以下是用于创建备份副本的方法.请注意,可以使用多个persistentStoreCoordinator打开存储,因此在进行备份时无需关闭它.恢复它显然需要先删除现有的商店.请注意,除了使用或不使用iCloud选项打开源存储之外,以下两种方法之间几乎没有区别.

/*! Creates a backup of the ICloud store

     @return Returns YES of file was migrated or NO if not.
     */
    - (bool)backupICloudStore {
        FLOG(@"backupICloudStore called");


        // Lets use the existing PSC
        NSPersistentStoreCoordinator *migrationPSC = [[NSPersistentStoreCoordinator alloc] initWithManagedobjectModel:self.managedobjectModel];

        // Open the store
        id sourceStore = [migrationPSC addPersistentStoreWithType:NSsqliteStoreType configuration:nil URL:[self icloudStoreURL] options:[self icloudStoreOptions] error:nil];

        if (!sourceStore) {

            FLOG(@" Failed to add old store");
            migrationPSC = nil;
            return FALSE;
        } else {
            FLOG(@" Successfully added store to migrate");

            NSError *error;

            FLOG(@" About to migrate the store...");
            id migrationSuccess = [migrationPSC migratePersistentStore:sourceStore toURL:[self backupStoreURL] options:[self localStoreOptions] withType:NSsqliteStoreType error:&error];

            if (migrationSuccess) {
                FLOG(@"store successfully backed up");
                migrationPSC = nil;
                // Now reset the backup preference
                [[NSUserDefaults standardUserDefaults] setBool:NO forKey:_makeBackupPreferenceKey];
                [[NSUserDefaults standardUserDefaults] synchronize];
                return TRUE;
            }
            else {
                FLOG(@"Failed to backup store: %@,%@",error,error.userInfo);
                migrationPSC = nil;
                return FALSE;
            }

        }
        migrationPSC = nil;
        return FALSE;
    }
    /*! Creates a backup of the Local store

     @return Returns YES of file was migrated or NO if not.
     */
    - (bool)backupLocalStore {
        FLOG(@"backupLocalStore called");


        // Lets use the existing PSC
        NSPersistentStoreCoordinator *migrationPSC = [[NSPersistentStoreCoordinator alloc] initWithManagedobjectModel:self.managedobjectModel];

        // Open the store
        id sourceStore = [migrationPSC addPersistentStoreWithType:NSsqliteStoreType configuration:nil URL:[self localStoreURL] options:[self localStoreOptions] error:nil];

        if (!sourceStore) {

            FLOG(@" Failed to add old store");
            migrationPSC = nil;
            return FALSE;
        } else {
            FLOG(@" Successfully added store to migrate");

            NSError *error;

            FLOG(@" About to migrate the store...");
            id migrationSuccess = [migrationPSC migratePersistentStore:sourceStore toURL:[self backupStoreURL] options:[self localStoreOptions] withType:NSsqliteStoreType error:&error];

            if (migrationSuccess) {
                FLOG(@"store successfully backed up");
                migrationPSC = nil;
                // Now reset the backup preference
                [[NSUserDefaults standardUserDefaults] setBool:NO forKey:_makeBackupPreferenceKey];
                [[NSUserDefaults standardUserDefaults] synchronize];
                return TRUE;
            }
            else {
                FLOG(@"Failed to backup store: %@,error.userInfo);
                migrationPSC = nil;
                return FALSE;
            }

        }
        migrationPSC = nil;
        return FALSE;
    }

/**  Sets the selected file as the current store.
 Creates a backup of the current store first.

 @param fileURL The URL for the file to use.
 */
- (BOOL)restoreFile:(NSURL *)fileURL {
    FLOG(@" called");

    // Check if we are using iCloud
    if (_isCloudEnabled) {
        FLOG(@" using iCloud store so OK to restore");
        NSURL *currentURL = [self storeURL];
        FLOG(@" currentURL is %@",currentURL);

        FLOG(@" URL to use is %@",fileURL);

        [self saveContext];

        [self backupCurrentStoreWithNoCheck];

        // Close the current store and delete it
        _persistentStoreCoordinator = nil;
        _managedobjectContext = nil;

        [self removeICloudStore];

        [self moveStoreFiletoICloud:fileURL delete:NO backup:NO];


    } else {
        FLOG(@" using local store so OK to restore");
        NSURL *currentURL = [self storeURL];
        FLOG(@" currentURL is %@",fileURL);

        [self saveContext];

        [self backupCurrentStoreWithNoCheck];

        // Close the current store and delete it
        _persistentStoreCoordinator = nil;
        _managedobjectContext = nil;

        NSError *error = nil;
        NSFileManager *fm = [[NSFileManager alloc] init];

        // Delete the current store file
        if ([fm fileExistsAtPath:[currentURL path]]) {
            FLOG(@" target file exists");
            if (![fm removeItemAtURL:currentURL error:&error]) {
                FLOG(@" error unable to remove current store file");
                NSLog(@"Error removing item Error: %@,error.userInfo);
                return FALSE;
            } else {
                FLOG(@" current store file removed");
            }
        }

        //
        //simply copy the file over
        BOOL copySuccess = [fm copyItemAtPath:[fileURL path]
                                       toPath:[currentURL path]
                                        error:&error];
        if (copySuccess) {
            FLOG(@" replaced current store file successfully");
            //[self postFileUpdateNotification];
        } else {
            FLOG(@"Error copying items Error: %@,error.userInfo);
            return FALSE;
        }
    }

    // Now open the store again

    [self openPersistentStore];

    return TRUE;
}