응용 프로그램을 다시 실행하면 데이터가 손실됩니다 (코어 데이터)

Question

가이가 괜찮 으면 좋겠어요.

저는 iPhone 개발에 익숙하지 않습니다. 코어 데이터를 사용하여 간단한 응용 프로그램을 만들고 있습니다. 데이터를 저장할 때 응용 프로그램을 실행하는 동안 문제없이 작동하고 데이터를 검색 할 수 있습니다. 그러나 응용 프로그램을 다시 시작하면 모든 데이터가 손실됩니다.

응용 프로그램 시작시 ViewDidLoad 함수에서 작업중인 응용 프로그램에서 검색하는 것과 동일한 함수로 데이터를 검색하고 있습니다.

데이터 저장 방법 :

NSManagedObjectContext *context=[app managedObjectContext]; 
    Contacts *data=[NSEntityDescription insertNewObjectForEntityForName:@"Contacts" inManagedObjectContext:context]; 
    if(nameField.text.length <=0 || phoneField.text.length <=0) 
    { 

     UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"Warning!" message:@"Please enter some data." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles: nil]; 
     [alert show]; 
    } 
    else 
    { 
     data.name = nameField.text; 
     data.phone = phoneField.text; 
     NSLog(data.name); 
     NSLog(data.phone); 
     [self.navigationController popToRootViewControllerAnimated:YES]; 

    } 

데이터를 검색하는 방법 :

NSEntityDescription *entity=[NSEntityDescription entityForName:@"Database" inManagedObjectContext:context]; 

    NSFetchRequest *fetchRequest=[[NSFetchRequest alloc]init]; 

    [fetchRequest setFetchBatchSize:20]; 

    [fetchRequest setEntity:entity]; 

    NSSortDescriptor *sorting = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; 

    NSArray *sorted_Array=[NSArray arrayWithObject:sorting]; 

    [fetchRequest setSortDescriptors:sorted_Array]; 

    NSError *error; 

    NSMutableArray *tArray=[[context executeFetchRequest:fetchRequest error:&error]mutableCopy]; 

    [self setArray:tArray]; 
    [self.tableView reloadData]; 

앱 위임 코드

#import "ZAppDelegate.h" 
#import "Contacts.h" 

@implementation ZAppDelegate 

@synthesize window = _window; 
@synthesize managedObjectContext = __managedObjectContext; 
@synthesize managedObjectModel = __managedObjectModel; 
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator; 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 
    // Override point for customization after application launch. 

    TableViewController *TVC=[[TableViewController alloc]init]; 

    TVC.MOcontext=self.managedObjectContext; 

    UINavigationController *nvgc=[[UINavigationController alloc]initWithRootViewController:TVC]; 
    self.window.rootViewController=nvgc; 


    self.window.backgroundColor = [UIColor whiteColor]; 
    [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 
{ 
    /* 
    Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface. 
    */ 
} 

- (void)applicationWillTerminate:(UIApplication *)application 
{ 
    // Saves changes in the application's managed object context before the application terminates. 
    [self saveContext]; 
} 

- (void)saveContext 
{ 
    NSError *error = nil; 
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext; 
    if (managedObjectContext != nil) 
    { 
     if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) 
     { 
      /* 
      Replace this implementation with code to handle the error appropriately. 

      abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 
      */ 
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      abort(); 
     } 
    } 
} 

#pragma mark - Core Data stack 

/** 
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; 
    } 
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Diary" withExtension:@"momd"]; 
    __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:@"Diary.sqlite"]; 

    NSError *error = nil; 
    __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 
    if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) 
    { 
     /* 
     Replace this implementation with code to handle the error appropriately. 

     abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 

     Typical reasons for an error here include: 
     * The persistent store is not accessible; 
     * The schema for the persistent store is incompatible with current managed object model. 
     Check the error message to determine what the actual problem was. 


     If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory. 

     If you encounter schema incompatibility errors during development, you can reduce their frequency by: 
     * Simply deleting the existing store: 
     [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil] 

     * Performing automatic lightweight migration by passing the following dictionary as the options parameter: 
     [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; 

     Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details. 

     */ 
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     abort(); 
    }  

    return __persistentStoreCoordinator; 
} 

#pragma mark - Application's Documents directory 

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

@end 

여기에 어떤 문제가 있습니까? 가능한 한 빨리 좋은 답변을 얻기를 바랍니다.

Answer 1

응용 프로그램의 수명주기에서 NSManagedObjectContext에 save을 호출해야합니다. 그렇지 않으면 변경 사항이 NSPersistentStore에 유지되지 않습니다. 예를 들어 응용 프로그램 대리자의 applicationDidEnterBackground: 메서드에 있습니다.

NSError *saveError = nil; 
if(![[self managedObjectContext] save:&saveError]) { 
    // deal with error... 
} 

난 당신이 코드에 저장 가하고 있습니다 어디

Answer 2

을 볼 수 없습니다 ... 응용 프로그램 대리자를 설정하고 애플 템플릿처럼 코어 데이터 스택 유지하고 있으리라 믿고있어. 저장하려면 managedcontext에 알려줘야합니다. 당신이하는 일은 앱과 디자인에 달려 있습니다. 어딘가에 이미 앱에 있다고 생각된다면 NSLog를 추가하여 디버깅하거나 디버거 도구를 사용하여 실제로 코드를 실행하십시오.

쉬운 수정입니다. 행운을 빕니다. AppDelegate에에서

Answer 3

:

- (void)applicationWillTerminate:(UIApplication *)application 
{ 
    // Saves changes in the application's managed object context before the application terminates. 
    [self saveContext]; 
} 

-saveContext은 엑스 코드의 템플릿의 이전 버전에서 -save 수 있습니다.

---

그리고 무엇보다, 당신은 단지 다른 클래스에서 -save 또는 -saveContent 메서드를 호출 할 수 있습니다

[(AppDelegate *)[UIApplication sharedApplication] saveContext]; 

Answer 4

NSManagedObjectContext 스크래치 패드를 제공합니다 : 당신이 당신의 개체를 원하는대로 당신이 할 수 있지만, 결국 그것을 구해야합니다. NSManagedObjectContext에 대한 모든 변경은 저장할 때까지 일시적입니다. 당신의 방법의 끝이 추가보십시오 :

if (![context save:&error]) { 
NSLog(@"Couldn't save: %@", error); 
} 

Answer 5

이 Context가
CoreDataManager를 저장할 필요가 * 컨텍스트 = [CoreDataManager sharedInstance]
...
..
...
...
.....
...
[컨텍스트 saveContext];