Datos perdidos cuando relanzo la aplicación (Datos principales)

Question

Guy espero que esté bien.

Soy nuevo en el desarrollo de iPhone. Estoy creando una aplicación simple usando datos centrales. Durante la aplicación cuando guardo datos, funciona bien, y luego recupero datos, también funciona bien. Pero cuando reinicio mi aplicación, todos los datos se pierden.

Al iniciar la aplicación, en la función ViewDidLoad estoy recuperando datos con la misma función que recupero durante la aplicación en funcionamiento. Método

Almacenamiento de datos:

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]; 

    } 

Recuperando método de Datos:

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]; 

App Código Delegado

#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 

¿Hay algo mal aquí? Espero obtener buenas respuestas lo antes posible.

Answer 1

En algún momento del ciclo de vida de la aplicación, debe llamar al save en el NSManagedObjectContext o sus cambios no se conservarán en el NSPersistentStore. Por ejemplo, en el método applicationDidEnterBackground: del delegado de la aplicación.

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

Estoy asumiendo que su delegado aplicación configura y mantiene la pila de los datos básicos, como las plantillas de Apple hacen ...

Answer 2

no veo donde está poniendo el salve en el código. Necesita decirle al managedcontext para guardar. Donde lo haces depende de tu aplicación y el diseño. Si crees que ya está en tus aplicaciones en alguna parte, agrega un poco de NSLog para tratar de depurar o usar la herramienta de depuración para entrar en tu código.

Es una solución fácil. Buena suerte.

Answer 3

En su AppDelegate:

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

El -saveContext podría ser -save en la versión anterior de la plantilla de Xcode.

---

Y lo que es más, usted puede llamar al método -save o -saveContent en otras clases:

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

Answer 4

El NSManagedObjectContext proporciona un rasguño-pad: usted puede hacer lo que quiera con sus objetos, pero Necesito guardarlo al final. Cualquier cambio que realice en un NSManagedObjectContext es temporal hasta que lo guarde. Trate de añadir esto al final de su método:

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

Answer 5

este contexto tiene que ser salvado
CoreDataManager * context = [CoreDataManager sharedInstance];
...
..
...
...
.....
...
[contexto saveContext];