Xcode核心数据:将现有XML更改为Sqlite(将NSXMLStoreType更改为NSSQLiteStoreType) [英] Xcode Core Data: Change existing XML to Sqlite (NSXMLStoreType to NSSQLiteStoreType)

问题描述

在我的第一个应用程序中，我在持久性存储协调器中使用了NSXMLStoreType.

On my first app I used within my persistant store coordinater a NSXMLStoreType.

[storeCooordinator addPersistentStoreWithType:NSXMLStoreType configuration:nil URL:storeURL options:options error:nil];

现在，我想更改为NSSQLiteStoreType:

Now, I like to change to a NSSQLiteStoreType:

[storeCooordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:nil];

如果我只是更改商店类型，则应用程序将崩溃.那我该怎么办?我可以做一次吗?

The app crashes, if I simply change the store type. So what I have to do? May I have to do once:

• 检查旧商店是否存在，并且
• 如果是，请将其转换为sqlite和
• 随后删除旧的xml存储吗?

我不知道如何将其转换为sqlite.型号是相同的.

I have no idea how to convert it to sqlite. The models are the same.

编辑&答案

我使用此解决方案来迁移数据库(感谢Volker )

I use this solution to migrate once the database (thanks to Volker)

//-> applicationFilesDirectory is the url to the documents directory

NSURL* oldURL = [applicationFilesDirectory URLByAppendingPathComponent:@"DBName1.xml"];
NSURL* newURL = [applicationFilesDirectory URLByAppendingPathComponent:@"DBName2.sqlite"];
NSError *error = nil;
NSFileManager * fileManager = [NSFileManager defaultManager];

        //-> if file exists            
        if ([fileManager fileExistsAtPath:[oldURL path]]) {
            NSLog(@"File is here");

            NSManagedObjectModel* managedModel = [NSManagedObjectModel mergedModelFromBundles:nil];
            NSPersistentStoreCoordinator* tempCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:managedModel];

            id xmlStore =  [tempCoordinator addPersistentStoreWithType:NSXMLStoreType configuration:nil URL:oldURL options:options error:nil];

            [tempCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:newURL options:options error:nil];

            if ( ![tempCoordinator migratePersistentStore:xmlStore toURL:newURL options:options withType:NSSQLiteStoreType error:&error] ) {
                //-> delete the old file from directory
                [fileManager removeItemAtURL:oldURL error:NULL];
            }
        }

推荐答案

您可以按照如果这应该自动发生，则需要在启动时添加迁移.

If this should happen automatically, you will need to add the migration at startup.

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