Wie kann ich Core Data in ein bereits erstelltes iOS-Projekt in Xcode einbinden?

Question

Ich habe vergessen, Core Data einzubeziehen, und jetzt habe ich die Hälfte des Projekts abgeschlossen und möchte es jetzt aufnehmen.

Ist es jetzt möglich, Core Data einzubeziehen? Wenn ja, kann mir jemand sagen, wie ich das mache?

Answer 1

Xcode 4.3.2 Hinzufügen von Core-Data-Framework.

Wählen Sie Ziel-> Übersichtsfenster-> Verknüpfte Frameworks & Bibliotheken.

In der oberen Bild Coredata Framework bereits hinzugefügt. U kann auf '+' klicken, um Rahmen Ihrer Wahl hinzuzufügen.

EINMALIG ANKLEBEN '+' KNOPF U'LL SIEHE UNTEN IM BILDSCHIRM.

Um neue Dateien, um es zu File-> Neue Datei gehen hinzufügen -> iOS tab-> Coredata setion.You kann

der ur Wahl Datei

Answer 2

hinzufügen Coredata Rahmen das Projekt, erstellen Sie dann eine .xdatamodeld-Datei (Datei-> Neu-> CoreData-> Datenmodell). Nennen Sie es DataModel. Dann eine Singleton-Klasse erstellen, die alle Datenoperationen Persistenz werden handhaben:

.h

// 
    // DataAccessLayer.h 
    // 
    // 
    // Copyright (c) 2012 __MyCompanyName__. All rights reserved. 
    // 

    #import <Foundation/Foundation.h> 
    #import <CoreData/CoreData.h> 

    @interface DataAccessLayer : NSObject 

    @property (strong, nonatomic) NSManagedObjectContext *managedObjectContext; 
    @property (strong, nonatomic) NSManagedObjectModel *managedObjectModel; 
    @property (strong, nonatomic) NSPersistentStoreCoordinator *storeCoordinator; 

    + (DataAccessLayer *)sharedInstance; 
    - (void)saveContext; 

    @end 

.m

// 
// DataAccessLayer.m 
// 
// 
// Created by admin on 2/27/12. 
// Copyright (c) 2012 __MyCompanyName__. All rights reserved. 
// 

#import "DataAccessLayer.h" 
@interface DataAccessLayer() 
- (NSURL *)applicationDocumentsDirectory; 
@end 

@implementation DataAccessLayer 
@synthesize storeCoordinator; 
@synthesize managedObjectModel; 
@synthesize managedObjectContext; 

+ (DataAccessLayer *)sharedInstance { 
    __strong static DataAccessLayer *sharedInstance = nil; 
    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{ 
    sharedInstance = [[DataAccessLayer alloc] init]; 
    sharedInstance.storeCoordinator = [sharedInstance persistentStoreCoordinator]; 
    sharedInstance.managedObjectContext = [sharedInstance managedObjectContext]; 
    }); 
    return sharedInstance; 
} 

#pragma mark - Core Data 

- (void)saveContext { 
    NSError *error = nil; 
    if (managedObjectContext != nil) 
    { 
    if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) 
    { 
     NSLog(@"error: %@", error.userInfo); 
     /* 
     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. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. 
     */ 
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Oops!" 
                 message:@"Something has gone terribly wrong! You need to reinstall the app in order for it to work properly." 
                delegate:nil 
              cancelButtonTitle:@"Close." 
              otherButtonTitles:nil, nil]; 
     [alert show]; 
    } 
    } 
} 

#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; 
    } 

    if (storeCoordinator != nil) 
    { 
    self.managedObjectContext = [[NSManagedObjectContext alloc] init]; 
    [managedObjectContext setPersistentStoreCoordinator:storeCoordinator]; 
    } 
    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:@"DataModel" withExtension:@"momd"]; 
    self.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 (storeCoordinator != nil) 
    { 
    return storeCoordinator; 
    } 

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

    NSError *error = nil; 
    self.storeCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 
    if (![storeCoordinator 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. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. 

    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]); 
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Oops!" 
                message:@"Something has gone terribly wrong! You need to reinstall the app in order for it to work properly." 
                delegate:nil 
              cancelButtonTitle:@"Close." 
              otherButtonTitles:nil, nil]; 
    [alert show]; 
    }  

    return storeCoordinator; 
} 

#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 

Answer 3

Sowohl die hp iOS Coder 's und Eugene' s Antworten sind richtig!

A Core Data-Datei (oder Projekt) konfiguriert ist, um:

1. Link zu und schließt die Kerndaten Rahmen (und tut dies als Import-Anweisung in dem Projekt .pch Datei)
2. die AppDelegate Header (H) umfaßt Eigenschaften erklärt ein context, model und coordinator (wie oben)
3. die app delegate ‚s .m definiert saveContext, managedObjectContext, managedObjectModel, persistentStoreCoordinator, applicationDocumentDirectory Funktionen/Methoden
4. ein Datenmodell, wie oben