Core data boiler plate

DBController.h

//
//  DBController.h
//
//  Created by Jesse Crocker on 3/31/13.
//  Copyright (c) 2013 Jesse Crocker. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface DBController : NSObject
@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;


- (NSManagedObjectContext *)managedObjectContext;
- (BOOL)saveMainContext;
- (BOOL)saveContext:(NSManagedObjectContext*)conext;


@end

DBController.m

//
//  DBController.m
//  WeList
//
//  Created by Jesse Crocker on 3/31/13.
//  Copyright (c) 2013 Jesse Crocker. All rights reserved.
//

#import "DBController.h"
#import <CoreData/CoreData.h>

#define MODEL_NAME @"WeList"
#define STORE_NAME @"WeList.sqlite"

@interface DBController () {
  NSManagedObjectModel *_managedObjectModel;
  NSPersistentStoreCoordinator *_persistentStoreCoordinator;
  NSManagedObjectContext *_managedObjectContext;
}

@end

@implementation DBController

#pragma mark - public interface
- (BOOL)saveContext:(NSManagedObjectContext*)conext {
  NSError *error = nil;
  NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
  if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
    NSLog(@"error saving context %@, %@", error, [error userInfo]);
    return NO;
  }
  
  return YES;
}


- (BOOL)saveMainContext {
  return [self saveContext:self.managedObjectContext];
}


#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];
  } else {
    NSLog(@"Could not get persistent store 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:MODEL_NAME 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:STORE_NAME];
  
  NSError *error = nil;
  _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
  if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
                                                 configuration:nil
                                                           URL:storeURL
                                                       options:nil
                                                         error:&error]) {
    NSLog(@"Error creating persistent store coordinator %@, %@", error, [error userInfo]);
    if([[NSFileManager defaultManager] fileExistsAtPath:[storeURL path]]) {
      [[NSFileManager defaultManager] moveItemAtURL:storeURL
                                              toURL:[[self applicationDocumentsDirectory] URLByAppendingPathComponent:[STORE_NAME stringByAppendingPathExtension:@"backup"]]
                                              error:nil];
      return [self persistentStoreCoordinator];
    } else {
      return nil;
    }
  }
  
  return _persistentStoreCoordinator;
}


#pragma mark -
- (NSURL *)applicationDocumentsDirectory {
  return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}


@end