Data Providers and Presenters

FRKCoreDataProvider.h

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

@interface FRKCoreDataProvider : NSObject <FRKDataProvider, FRKSectionInfoProvider>

- (instancetype)initWithFetchRequest:(NSFetchRequest *)fetchRequest moc:(NSManagedObjectContext *)fetchMOC;
- (instancetype)initWithFetchRequest:(NSFetchRequest *)fetchRequest moc:(NSManagedObjectContext *)fetchMOC sectionKeypath:(NSString *)section;

@end

FRKCoreDataProvider.m

#import "FRKCoreDataProvider.h"

@interface FRKCoreDataProvider ()

@property(nonatomic, strong) NSFetchedResultsController *fetchedResultsController;

@property(nonatomic, strong) NSManagedObjectContext *fetchingMOC;
@property(nonatomic, strong) NSFetchRequest *fetchRequest;
@property(nonatomic, copy) NSString *sectionKeypath;

@end

@implementation FRKCoreDataProvider

- (instancetype)initWithFetchRequest:(NSFetchRequest *)fetchRequest
                                 moc:(NSManagedObjectContext *)fetchMOC {
    return [self initWithFetchRequest:fetchRequest moc:fetchMOC sectionKeypath:nil];
}

- (instancetype)initWithFetchRequest:(NSFetchRequest *)fetchRequest
                                 moc:(NSManagedObjectContext *)fetchMOC
                      sectionKeypath:(NSString *)section {
    self = [super init];
    if (!self) {
        return nil;
    }
    
    _fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                                    managedObjectContext:fetchMOC
                                                                      sectionNameKeyPath:section
                                                                               cacheName:nil];
    
    return self;
}

#pragma mark - FRKDataProvider

- (void)loadDataWithCompletion:(void (^)(NSArray *errors))completion {
    NSError *error;
    BOOL success = [self.fetchedResultsController performFetch:&error];
   
    if (success) {
        completion(nil);
    } else {
        NSLog(@"Something isn't right :(");
        completion(error);
    }
}

- (id)itemAtIndexPath:(NSIndexPath *)indexPath {
    return [self.fetchedResultsController objectAtIndexPath:indexPath];
}

- (NSIndexPath *)indexForItem:(id)item {
    return [self.fetchedResultsController indexPathForObject:item];
}

#pragma mark - FRKSectionInfoProvider

- (NSInteger)numberOfSections {
    return [[self.fetchedResultsController sections] count];
}

- (NSInteger)numberOfItemsInSection:(NSInteger)section {
    id <NSFetchedResultsSectionInfo> sectionInfo = [self.fetchedResultsController.sections objectAtIndex:section];
    
    return [sectionInfo numberOfObjects];
}

@end