Core Data helper categories

NSManagedObject+MAK.h

//
//  NSManagedObject+MAK.h
//
//  Created by Justin Driscoll on 2/21/12.
//

#import <CoreData/CoreData.h>


@interface NSManagedObject (MAK)

+ (void)loadSeedsFromPath:(NSString *)path inContext:(NSManagedObjectContext *)context;
+ (NSString *)entityName;

+ (NSArray *)fetchAllInContext:(NSManagedObjectContext *)context;
+ (NSArray *)fetchObjectsInContext:(NSManagedObjectContext *)context sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate;

+ (NSUInteger)fetchCountInContext:(NSManagedObjectContext *)context withPredicate:(NSPredicate *)predicate;

+ (id)fetchFirstObjectInContext:(NSManagedObjectContext *)context sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate;

+ (id)newObjectInContext:(NSManagedObjectContext *)context;

- (void)deleteObject;

@end

NSManagedObject+MAK.m

//
//  NSManagedObject+MAK.m
//
//  Created by Justin Driscoll on 2/21/12.
//

#import "NSManagedObject+MAK.h"
#import "NSManagedObjectContext+MAK.h"


@implementation NSManagedObject (MAK)

+ (void)loadSeedsFromPath:(NSString *)path inContext:(NSManagedObjectContext *)context
{
    NSDictionary *seeds = [[NSDictionary alloc] initWithContentsOfFile:path];
    
    NSArray *Entities = [seeds allKeys];
    for (NSString *entityName in Entities) {
        for (NSDictionary *propertyDictionary in (NSDictionary *)[seeds objectForKey:entityName]) {
            NSManagedObject *object = [NSEntityDescription insertNewObjectForEntityForName:entityName
                                                                    inManagedObjectContext:context];
            NSArray *propertyNames = [propertyDictionary allKeys];
            for (NSString *propertyName in propertyNames) {
                [object setValue:[propertyDictionary objectForKey:propertyName] forKey:propertyName];
            }
        }
    }
}

+ (NSString *)entityName
{
    return NSStringFromClass([self class]);
}

+ (NSArray *)fetchAllInContext:(NSManagedObjectContext *)context
{
    return [self fetchObjectsInContext:context sortedBy:nil withPredicate:nil];
}

+ (NSArray *)fetchObjectsInContext:(NSManagedObjectContext *)context sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate
{
    return [context fetchObjectsWithEntityName:[self entityName] sortedBy:sortDescriptors withPredicate:predicate];
}

+ (NSUInteger)fetchCountInContext:(NSManagedObjectContext *)context withPredicate:(NSPredicate *)predicate
{
    return [context fetchCountWithEntityName:[self entityName] andPredicate:predicate];
}

+ (id)fetchFirstObjectInContext:(NSManagedObjectContext *)context sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate
{
    return [context fetchFirstObjectWithEntityName:[self entityName] sortedBy:sortDescriptors withPredicate:predicate];
}

+ (id)newObjectInContext:(NSManagedObjectContext *)context
{
    return [context insertNewObjectWithEntityName:[self entityName]];
}

- (void)deleteObject
{
    [self.managedObjectContext deleteObject:self];
}

@end

NSManagedObjectContext+MAK.h

//
//  NSManagedObjectContext+MAK.m
//
//  Created by Justin Driscoll on 12/16/11.
//

#import <CoreData/CoreData.h>


@interface NSManagedObjectContext (MAK)

- (id)insertNewObjectWithEntityName:(NSString *)entityName;

- (NSArray *)fetchObjectArrayWithRequest:(NSFetchRequest *)request;
- (NSUInteger)fetchCountWithRequest:(NSFetchRequest *)request;

- (NSFetchRequest *)fetchRequestForEntity:(NSEntityDescription *)entity;
- (NSFetchRequest *)fetchRequestForEntityName:(NSString *)entityName;
- (NSFetchRequest *)fetchRequestForEntityName:(NSString *)entityName sortDescriptors:(NSArray *)sortDescriptors andPredicate:(NSPredicate *)predicate;

- (NSArray *)fetchObjectsWithEntityName:(NSString *)entityName sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate;

- (id)fetchFirstObjectWithEntityName:(NSString *)entityName sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate;

- (NSUInteger)fetchCountWithEntityName:(NSString *)entityName andPredicate:(NSPredicate *)predicate;

@end

NSManagedObjectContext+MAK.m

//
//  NSManagedObjectContext+MAK.m
//
//  Created by Justin Driscoll on 12/16/11.
//

#import "NSManagedObjectContext+MAK.h"


@implementation NSManagedObjectContext (MAK)

- (id)insertNewObjectWithEntityName:(NSString *)entityName
{
    return [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:self];
}

#pragma mark -

- (NSArray *)fetchObjectArrayWithRequest:(NSFetchRequest *)request
{
	NSError *error;
	NSArray *results = [self executeFetchRequest:request error:&error];
	
	NSAssert(error == nil, [error description]);
	
	return results;
}

- (NSUInteger)fetchCountWithRequest:(NSFetchRequest *)request
{
    NSError *error = nil;
    NSUInteger result = [self countForFetchRequest:request error:&error];

    NSAssert(error == nil, [error description]);

    return result;
}

#pragma mark -

- (NSFetchRequest *)fetchRequestForEntity:(NSEntityDescription *)entity
{
	NSFetchRequest *request = [[NSFetchRequest alloc] init];
	[request setEntity:entity];
	
	return request;
}

- (NSFetchRequest *)fetchRequestForEntityName:(NSString *)entityName
{
	NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:self];
	return [self fetchRequestForEntity:entity];
}

- (NSFetchRequest *)fetchRequestForEntityName:(NSString *)entityName sortDescriptors:(NSArray *)sortDescriptors andPredicate:(NSPredicate *)predicate
{
    NSFetchRequest *request = [self fetchRequestForEntityName:entityName];
    
    if (sortDescriptors)
		[request setSortDescriptors:sortDescriptors];
	
	if (predicate)
		[request setPredicate:predicate];
    
    return request;
}

#pragma mark -

- (NSArray *)fetchObjectsWithEntityName:(NSString *)entityName sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate
{
	NSFetchRequest *request = [self fetchRequestForEntityName:entityName sortDescriptors:sortDescriptors andPredicate:predicate];
	return [self fetchObjectArrayWithRequest:request];
}

- (id)fetchFirstObjectWithEntityName:(NSString *)entityName sortedBy:(NSArray *)sortDescriptors withPredicate:(NSPredicate *)predicate
{
    NSFetchRequest *request = [self fetchRequestForEntityName:entityName sortDescriptors:sortDescriptors andPredicate:predicate];
    [request setFetchLimit:1];
    
	NSArray *results = [self fetchObjectArrayWithRequest:request];	
    
    if ([results count] == 0)
        return nil; 
    
    return [results lastObject]; 
}

#pragma mark - 

- (NSArray *)fetchObjectsWithEntityName:(NSString *)entityName usingPredicate:(NSPredicate *)predicate sortedBy:(NSString *)sortDescriptorKey ascending:(BOOL)ascending
{
    NSArray *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:sortDescriptorKey ascending:ascending];
    return [self fetchObjectsWithEntityName:entityName sortedBy:@[sortDescriptor] withPredicate:predicate];
}

- (id)fetchFirstObjectWithEntityName:(NSString *)entityName usingPredicate:(NSPredicate *)predicate sortedBy:(NSString *)sortDescriptorKey ascending:(BOOL)ascending
{
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:sortDescriptorKey ascending:ascending];
    return [self fetchFirstObjectWithEntityName:entityName sortedBy:@[sortDescriptor] withPredicate:predicate];
}

#pragma mark - 

- (NSUInteger)fetchCountWithEntityName:(NSString *)entityName andPredicate:(NSPredicate *)predicate
{
    NSFetchRequest *request = [self fetchRequestForEntityName:entityName sortDescriptors:nil andPredicate:predicate];
    return [self fetchCountWithRequest:request];
}

@end