我想为我的应用程序的用户提供创建核心数据数据库备份的可能性，特别是在他切换到新设备等的情况下。
我该怎么做？特别是如何重新导入该文件？我的意思是让我们说他制作数据库的备份副本，然后改变了大量的东西，并希望重置为以前保存的备份副本。我该怎么做？
THX！
答案 0 :(得分：5)
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/
BTW使用migratePersistentStore API来制作/导入备份比使用ICloud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。
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, 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 %@", currentURL);
FLOG(@" URL to use 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, 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, error.userInfo);
return FALSE;
}
}
// Now open the store again
[self openPersistentStore];
return TRUE;
}
答案 1 :(得分：1)
您使用的持久存储是什么（二进制，SQLite等）;它只是文件系统上的一个文件。您可以随时复制它。
如果您在iOS 7中使用SQLite，请确保复制与其关联的其他文件，因为它们是随附的日志文件。如果您使用二进制文件，则只有一个文件。
如果你只是复制文件没有导入步骤，你只需将其复制以恢复它。
还有更多高级设计，例如将整个数据库导出为可移植的东西，例如JSON，但这是一个不同的主题。
我已经使用了标准的Xcode核心数据模板，所以根据我刚刚检查过的代码我正在使用SQLite。那么如何找到所有相关文件？或者你能告诉我一些示例代码如何复制和插回所需的文件？
您使用NSFileManager复制文件。您可以查看iOS模拟器应用程序中的文档目录，以查看所有文件的名称。或者您可以使用NSFileManager扫描文档目录，查找以相同文件名开头的所有内容（例如MyData.*）并将其复制到备份目录中。
至于示例代码，没有;查看NSFileManager的文档后，它只有几行代码。
答案 2 :(得分：0)
我在Apple示例code的帮助下创建了以下方法。这将备份核心数据文件，并将其放置到所需的路径。
雨燕5
/// Backing up store type to a new and unique location
/// The method is illustrated in the following code fragment, which shows how you can use migratePersistentStore to take a back up of a store and save it from one location to another.
/// If the old store type is XML, the example also converts the store to SQLite.
/// - Parameters:
/// - path: Where you want the backup to be done, please create a new unique directory with timestamp or the guid
/// - completion: Passes error in case of error or pass nil in case of success
class func backUpCoreDataFiles(path : URL, completion : @escaping (_ error : String?) -> ())
{
// Every time new container is a must as migratePersistentStore method will loose the reference to the container on migration
let container = NSPersistentContainer(name : "<YourDataModelName>")
container.loadPersistentStores
{ (storeDescription, error) in
if let error = error
{
fatalError("Failed to load store: \(error)")
}
}
let coordinator = container.persistentStoreCoordinator
let store = coordinator.persistentStores[0]
do
{
try coordinator.migratePersistentStore(store, to : path, options : nil, withType : NSSQLiteStoreType)
completion(nil)
}
catch
{
completion("\(Errors.coredataBackupError)\(error.localizedDescription)")
}
}