哪里可以放置代码配置永久存储迁移

Question

我已经在App Store上为许多客户创建并分发了一个Mac App，并且我需要向Core Data Model添加一个属性。我阅读了Apple提供的文档，可用here。

然而，它给这个代码块启用自动迁移：

NSError *error; 
NSPersistentStoreCoordinator *psc = <#The coordinator#>; 
NSURL *storeURL = <#The URL of a persistent store#>; 
NSDictionary *optionsDictionary = 
    [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] 
        forKey:NSMigratePersistentStoresAutomaticallyOption]; 

NSPersistentStore *store = [psc addPersistentStoreWithType:<#Store type#> 
           configuration:<#Configuration or nil#> 
           URL:storeURL 
           options:optionsDictionary 
           error:&error]; 

..我不知道往哪里放那。有人提到（在另一个线程中）它进入了PersistentStoreCoordinator，但是，我只是使用默认的Cocoa应用模板和“使用核心数据进行存储”。我必须创建自己的AppDelegate，并且永远不会看到有关PersistentStoreCoordinator的任何内容（但仍然没有，我尝试创建一个新应用程序来检查）。这里有帮助吗？我是Cocoa的新手，但是我的应用程序在没有PersistentStoreCoordinator的情况下工作得很好，这就是为什么我还没有实现一个。我确实有一个我创建的AppDelegate，但是当我将这些代码放在那里时，会引发很多错误。说明：/

EDIT（尼克）：这里是新代码：

我的头文件：

Answer 1

在这里你去：核心数据有关的报头和方法。

应用程序委托头 - 核心数据相关的部分

@interface CoreDataFirstStepsAppDelegate : NSObject <UIApplicationDelegate> 
{  
    // ... 
@private 
    NSManagedObjectContext *managedObjectContext_; 
    NSManagedObjectModel *managedObjectModel_; 
    NSPersistentStoreCoordinator *persistentStoreCoordinator_; 
} 

// ... 

@property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext; 
@property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel; 
@property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator; 

应用程序委托实现 - 核心数据相关的部分

/** 
Returns the managed object context for the application. 
If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application. 
*/ 
- (NSManagedObjectContext *)managedObjectContext { 

    if (managedObjectContext_ != nil) { 
     return managedObjectContext_; 
    } 

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator]; 
    if (coordinator != nil) { 
     managedObjectContext_ = [[NSManagedObjectContext alloc] init]; 
     [managedObjectContext_ setPersistentStoreCoordinator:coordinator]; 
    } 
    return managedObjectContext_; 
} 


/** 
Returns the managed object model for the application. 
If the model doesn't already exist, it is created from the application's model. 
*/ 
- (NSManagedObjectModel *)managedObjectModel { 

    if (managedObjectModel_ != nil) { 
     return managedObjectModel_; 
    } 
    NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"CoreDataFirstSteps" ofType:@"momd"]; 
    NSURL *modelURL = [NSURL fileURLWithPath:modelPath]; 
    managedObjectModel_ = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];  
    return managedObjectModel_; 
} 


/** 
Returns the persistent store coordinator for the application. 
If the coordinator doesn't already exist, it is created and the application's store added to it. 
*/ 
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator { 

    if (persistentStoreCoordinator_ != nil) { 
     return persistentStoreCoordinator_; 
    } 

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataFirstSteps.sqlite"]; 

    NSError *error = nil; 
    persistentStoreCoordinator_ = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 
    if (![persistentStoreCoordinator_ addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) { 

     NSError *error; 
     NSURL *storeURL = storeURL; 
     NSPersistentStoreCoordinator *psc = persistentStoreCoordinator_; 
     NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: 
           [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, 
           [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; 

     if (![psc addPersistentStoreWithType:NSSQLiteStoreType 
           configuration:nil 
             URL:storeURL 
            options:options 
             error:&error]) 
     { 
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      abort(); 
     }  
    }  

    return persistentStoreCoordinator_; 
} 

/** 
Returns the URL to the application's Documents directory. 
*/ 
- (NSURL *)applicationDocumentsDirectory { 
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; 
}