BookService.h

//
//  BookService.h
//  Libros
//
//  Created by Sean Hess on 1/10/13.
//  Copyright (c) 2013 Sean Hess. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Book.h"

@interface BookService : NSObject

+(BookService*)shared;
-(void)loadStore;

-(NSFetchRequest*)allBooks;
-(NSFetchRequest*)popular;
-(NSPredicate*)searchForText:(NSString*)text;

-(NSPredicate*)filterByType:(BookFilter)filter;

@end

BookService.m

//
//  BookService.m
//  Libros
//
//  Created by Sean Hess on 1/10/13.
//  Copyright (c) 2013 Sean Hess. All rights reserved.
//

#import "BookService.h"
#import "Book.h"
#import <RestKit/RestKit.h>
#import "ObjectStore.h"
#import "NSObject+Reflection.h"

@interface BookService ()
@end



@implementation BookService

+ (BookService *)shared
{
    static BookService *instance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[BookService alloc] init];
        [instance addMappings];
    });
    return instance;
}

- (void)addMappings {
    RKEntityMapping *bookMapping = [ObjectStore.shared mappingForEntityForName:@"Book"];
    [bookMapping setIdentificationAttributes:@[@"bookId"]];
    
    NSMutableArray * propertyNames = [NSMutableArray arrayWithArray:[_Book propertyNames]];
    NSIndexSet * indices = [propertyNames indexesOfObjectsPassingTest:^(NSString * name, NSUInteger idx, BOOL * stop) {
        return [name isEqualToString:@"descriptionText"];
    }];
    [propertyNames removeObjectsAtIndexes:indices];
    
    [bookMapping addAttributeMappingsFromArray:propertyNames];
    [bookMapping addAttributeMappingsFromDictionary:@{@"description": @"descriptionText"}];
    
    RKResponseDescriptor * responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:bookMapping pathPattern:@"/books" keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

    [ObjectStore.shared addResponseDescriptor:responseDescriptor];
    
    [ObjectStore.shared syncWithFetchRequest:self.allBooks forPath:@"/books"];
}

// So you can compose with compoundPredicates. Wahoo.
// Or just let the dumb view controllers do whatever they want. it's not THAT bad
// not that great either

// You can execute fetch requests right on the context
// OR you can make a fetched results controller and give it a fetch request

-(void)loadStore {
    [[ObjectStore shared].objectManager getObjectsAtPath:@"/books" parameters:nil success:^(RKObjectRequestOperation * operation, RKMappingResult *mappingResult) {
    } failure: ^(RKObjectRequestOperation * operation, NSError * error) {
        NSLog(@"FAILURE %@", error);
    }];
}

// has the sort descriptor built in
-(NSFetchRequest*)allBooks {
    NSFetchRequest * fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Book"];
    NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:@"title" ascending:YES];
    fetchRequest.sortDescriptors = @[descriptor];
    return fetchRequest;
}

-(NSFetchRequest*)popular {
    NSFetchRequest * fetchRequest = [self allBooks];
    return fetchRequest;
}

-(NSPredicate*)searchForText:(NSString*)text {
    return [NSPredicate predicateWithFormat:@"title BEGINSWITH[c] %@", [text lowercaseString]];
}

-(NSPredicate*)filterByType:(BookFilter)filter {
    if (filter == BookFilterHasAudio) return [NSPredicate predicateWithFormat:@"audioFiles > 0"];
    else if (filter == BookFilterHasText) return [NSPredicate predicateWithFormat:@"textFiles > 0"];
    else return nil;
}

@end

ObjectStore.h

//
//  ObjectStore.h
//  Libros
//
//  Created by Sean Hess on 1/11/13.
//  Copyright (c) 2013 Sean Hess. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <RestKit/RestKit.h>
#import "User.h"

@interface ObjectStore : NSObject

@property (strong, nonatomic) RKObjectManager* objectManager;
@property (strong, nonatomic) RKManagedObjectStore * objectStore;
@property (readonly, nonatomic) NSManagedObjectContext * context;

// use [UserService main] instead of calling this
@property (strong, nonatomic) User* mainUser;

+ (ObjectStore*)shared;
- (void)saveContext;

- (RKEntityMapping*)mappingForEntityForName:(NSString*)entityName;
- (void)addResponseDescriptor:(RKResponseDescriptor*)descriptor;

// Simple way to sync objects whose urls have no parameters
// Will delete anything not matched
- (void)syncWithFetchRequest:(NSFetchRequest*)request forPath:(NSString*)path;

@end

ObjectStore.m

//
//  ObjectStore.m
//  Libros
//
//  Created by Sean Hess on 1/11/13.
//  Copyright (c) 2013 Sean Hess. All rights reserved.
//
// I need to store some stuff
// it needs to know the application directory
// so a singleton with some initialization

#import "ObjectStore.h"
#import "Settings.h"

@interface ObjectStore()

@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;

@end




@implementation ObjectStore

@synthesize managedObjectModel = _managedObjectModel;

+ (ObjectStore *)shared
{
    static ObjectStore *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[ObjectStore alloc] init];
        [sharedInstance initObjectManager];
    });
    return sharedInstance;
}

- (void)initObjectManager {
    
    NSLog(@"ENDPOINT = %@", API_ENDPOINT);
    
    // Core Data Example
    // Initialize RestKIT
    self.objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:API_ENDPOINT]];
    self.objectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:self.managedObjectModel];
    self.objectManager.managedObjectStore = self.objectStore;
    
    // Other Initialization (move this to app delegate)
    [self.objectStore createPersistentStoreCoordinator];
    
    NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"Libros.sqlite"];
    NSError *error;
    NSPersistentStore *persistentStore = [self.objectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:nil withConfiguration:nil options:nil error:&error];
    NSAssert(persistentStore, @"Failed to add persistent store with error: %@", error);
    
    [self.objectStore createManagedObjectContexts];
    
    self.objectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:self.context];
}

// some demeters law, don't access the store and stuff, just add them here.
// See BookService for usage
- (RKEntityMapping *)mappingForEntityForName:(NSString *)entityName {
    return [RKEntityMapping mappingForEntityForName:entityName inManagedObjectStore:self.objectStore];
}

- (void)addResponseDescriptor:(RKResponseDescriptor *)descriptor {
    [self.objectManager addResponseDescriptor:descriptor];
}

- (void)syncWithFetchRequest:(NSFetchRequest *)request forPath:(NSString *)path {
    [self.objectManager addFetchRequestBlock:^(NSURL* url) {
        RKPathMatcher * matcher = [RKPathMatcher pathMatcherWithPattern:@"/books"];
        NSFetchRequest * matchingRequest = nil;
        BOOL match = [matcher matchesPath:[url relativePath] tokenizeQueryStrings:NO parsedArguments:nil];
        if (match) {
            matchingRequest = request;
        }
        return matchingRequest;
    }];
}

// 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:@"Libros" withExtension:@"momd"];
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    return _managedObjectModel;
}

- (NSManagedObjectContext *)context {
    // the mainQueueManagedObjectContext is a child of this one, but it doesn't persist. I'm not exactly sure what it is for.
    // either way, we need to use this one if we want things to save
    return self.objectStore.persistentStoreManagedObjectContext;
}

- (void)saveContext
{
    NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.context;
    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();
        } 
    }
}


@end