1

好吧，直奔主题……

这是我第一次使用 Magical Panda 的 Magical record 我遵循http://yannickloriot.com/2012/03/magicalrecord-how-to-make-programming-with-core-data-pleasant/的教程

这是我的代码

人.h

@property (nonatomic, retain) NSString * firstname;
@property (nonatomic, retain) NSString * lastname;
@property (nonatomic, retain) NSNumber * age;

AppDelegate.M

@implementation AppDelegate

- (void)dealloc
{
    [_window release];
    [_viewController release];
    [super dealloc];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
     [MagicalRecord setupCoreDataStackWithStoreNamed:@"MyDatabase.sqlite"];
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.viewController = [[JASidePanelController alloc] init];
    self.viewController.shouldDelegateAutorotateToVisiblePanel = NO;
  //  self.viewController = [[[ViewControllerCenter alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];
    self.viewController.centerPanel = [[UINavigationController alloc] initWithRootViewController:[[ViewControllerCenter alloc] init]];

    //UINavigationController *navContorller=[[UINavigationController alloc] initWithRootViewController:self.viewController];
    self.viewController.rightPanel = [[NetraRightWindow alloc] init];
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];

    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{


    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{

}

- (void)applicationWillTerminate:(UIApplication *)application
{
     [MagicalRecord cleanUp];
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

@end

这是我的保存方法：

-(void)fetchRecords{

   NSManagedObjectContext *localContext= [NSManagedObjectContext MR_defaultContext];

    // Create a new Person in the current thread context
    Person *person                          = [Person MR_createInContext:    [NSManagedObjectContext MR_defaultContext]];
    person.firstname                        = @"Test";
    person.lastname                         = @"merdeka123";
    person.age=[NSNumber numberWithInt:123];

    [[NSManagedObjectContext MR_defaultContext] MR_save];
    NSArray *Result=[Person MR_findAll];

    NSLog(@"Result==%@",Result);

结果::

2012-11-25 15:43:38.033 Trip[10491:15e03] Cok==(
    "<Person: 0x866fe40> (entity: Person; id: 0x866e170 <x-coredata://15583C03-3EB4-479B-9EF2-B0BC750FC987/Person/p1> ; data: <fault>)",
    "<Person: 0x866fe80> (entity: Person; id: 0x8670210 <x-coredata://15583C03-3EB4-479B-9EF2-B0BC750FC987/Person/p2> ; data: <fault>)",
    "<Person: 0x81471a0> (entity: Person; id: 0x815c2a0 <x-coredata://15583C03-3EB4-479B-9EF2-B0BC750FC987/Person/p3> ; data: {\n    age = 123;\n    firstname = Test;\n    lastname = merdeka123;\n    time = nil;\n})"
)

为什么它总是数据错误？这是魔法记录的问题吗？或者我的代码有什么问题？

4

2 回答 2

7

这不是错误——它是 Core Data 的一个特性，称为“故障”。这是苹果的描述：

故障减少了应用程序消耗的内存量。故障是表示尚未完全实现的托管对象的占位符对象，或表示关系的集合对象：

托管对象故障是适当类的实例，但其持久变量尚未初始化。关系故障是表示关系的集合类的子类。故障允许 Core Data 在对象图上设置边界。由于没有实现故障，托管对象故障消耗的内存较少，与故障相关的托管对象根本不需要在内存中表示。

如果您想查看每个 Person 对象，则必须专门访问它们。

于 2012-11-25T08:52:00.120 回答
1

我在 Magical 唱片中也一直犯错。经过大量的头部撞击。

[[NSManagedObjectContext defaultContext] saveToPersistentStoreWithCompletion:^(BOOL success, NSError *error) {

if (!success) {

NSLog(@"::: Error saving context :::");

}

}];

现在当你找到所有。通过在调试器中打印来检查对象。

Person *testObject = [Result objectAtIndex:0];
NSLog(@"%@", testObject.firstname);

这应该在调试器中打印您的结果。

于 2015-05-11T09:45:08.383 回答