Has anyone got iCloud core data syncing setup on Xcode 6 and iOS 8? (hopefully this isn't a duplicate post)
Where did iCloud Core Data storage option go?
I remember Core Data had an extra storage option called Core Data storage, but now in Xcode 6 it only seems to show key-value and document storage when I enable the iCloud toggle in Xcode 6.
So far, I don't know if I've setup Core Data iCloud correctly.
Xcode appears to have setup the iCloud containers in the iOS Developer Portal:
iCloud.com.xxxxxx.xxxxxxxx (note: I've replaced the actual strings with xxxx here)
My Xcode 6 iCloud "services" list shows no ticks next to:
Which one should we be using now since it doesn't list "core data" as a storage option?
In the "Containers" directly below the "services", it shows the following options greyed out:
I can't choose any option, it seems to force me to "Use default container".
Finally, Xcode seems to show ticks for:
So by Xcode's own automated process, it setup everything for me.
OK, so I read around and notice a iCloud stack written here:
https://github.com/mluisbrown/iCloudCoreDataStack
I've taken the necessary code and tried to adapt to my Core Data manager singleton:
+ (id)sharedModel;
+ (ALAssetsLibrary *)sharedLibrary;
@property (nonatomic, readonly) NSManagedObjectContext *mainContext;
@property (nonatomic, readonly) NSPersistentStoreCoordinator *storeCoordinator;
- (NSString *)modelName;
- (NSString *)pathToModel;
- (NSString *)storeFilename;
- (NSString *)pathToLocalStore;
#pragma mark - Entity Fetching Methods -
-(NSArray *)fetchEntityOfType:(NSString *)entityType UsingPredicated:(NSPredicate *)predicate sortBy:(NSString *)sortKey ascendingOrder:(BOOL)ascendingOrder;
@property (nonatomic, strong) NSManagedObjectModel *managedObjectModel;
- (NSString *)documentsDirectory;
@end
@implementation MLSAlbumsDataModel
@synthesize managedObjectModel = _managedObjectModel;
@synthesize storeCoordinator = _storeCoordinator;
@synthesize mainContext = _mainContext;
+ (id)sharedModel {
static MLSAlbumsDataModel *__instance = nil;
if (__instance == nil) {
__instance = [[MLSAlbumsDataModel alloc] init];
}
return __instance;
}
+ (ALAssetsLibrary *)sharedLibrary {
static ALAssetsLibrary *__instance = nil;
if (__instance == nil) {
__instance = [[ALAssetsLibrary alloc] init];
}
return __instance;
}
- (NSString *)modelName {
return @"Albums";
}
- (NSString *)pathToModel {
return [[NSBundle mainBundle] pathForResource:[self modelName] ofType:@"momd"];
}
- (NSString *)storeFilename {
return [[self modelName] stringByAppendingPathExtension:@"sqlite"];
}
- (NSString *)pathToLocalStore {
return [[self documentsDirectory] stringByAppendingPathComponent:[self storeFilename]];
}
- (NSString *)documentsDirectory {
NSString *documentsDirectory = nil;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
documentsDirectory = [paths objectAtIndex:0];
return documentsDirectory;
}
- (NSManagedObjectContext *)mainContext {
if(_mainContext == nil) {
_mainContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
_mainContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy;
// setup persistent store coordinator
DLog(@"SQLITE STORE PATH: %@", [self pathToLocalStore]);
NSURL *storeURL = [NSURL fileURLWithPath:[self pathToLocalStore]];
//_mainContext.persistentStoreCoordinator = [self storeCoordinator];
_mainContext.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
__weak NSPersistentStoreCoordinator *psc = self.mainContext.persistentStoreCoordinator;
// iCloud notification subscriptions
NSNotificationCenter *dc = [NSNotificationCenter defaultCenter];
[dc addObserver:self
selector:@selector(storesWillChange:)
name:NSPersistentStoreCoordinatorStoresWillChangeNotification
object:psc];
[dc addObserver:self
selector:@selector(storesDidChange:)
name:NSPersistentStoreCoordinatorStoresDidChangeNotification
object:psc];
[dc addObserver:self
selector:@selector(persistentStoreDidImportUbiquitousContentChanges:)
name:NSPersistentStoreDidImportUbiquitousContentChangesNotification
object:psc];
NSError* error;
// the only difference in this call that makes the store an iCloud enabled store
// is the NSPersistentStoreUbiquitousContentNameKey in options. I use "iCloudStore"
// but you can use what you like. For a non-iCloud enabled store, I pass "nil" for options.
// Note that the store URL is the same regardless of whether you're using iCloud or not.
// If you create a non-iCloud enabled store, it will be created in the App's Documents directory.
// An iCloud enabled store will be created below a directory called CoreDataUbiquitySupport
// in your App's Documents directory
[self.mainContext.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:storeURL
options:@{ NSPersistentStoreUbiquitousContentNameKey : @"iCloudStore" }
error:&error];
if (error) {
NSLog(@"error: %@", error);
}
_storeCoordinator = self.mainContext.persistentStoreCoordinator;
}
return _mainContext;
}
- (NSManagedObjectModel *)managedObjectModel {
if(_managedObjectModel == nil) {
NSURL *storeURL = [NSURL fileURLWithPath:[self pathToModel]];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:storeURL];
}
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)storeCoordinator {
if (_storeCoordinator == nil) {
// -----------------------------------------------------------------------------------------------------------------------------
// Code moved to managed object context code above
// -----------------------------------------------------------------------------------------------------------------------------
/*
DLog(@"SQLITE STORE PATH: %@", [self pathToLocalStore]);
NSURL *storeURL = [NSURL fileURLWithPath:[self pathToLocalStore]];
NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
NSError *error = nil;
if (![psc addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
NSDictionary *userInfo = [NSDictionary dictionaryWithObject:error forKey:NSUnderlyingErrorKey];
NSString *reason = @"Could not create persistent store";
NSException *exc = [NSException exceptionWithName:NSInternalInconsistencyException reason:reason userInfo:userInfo];
@throw exc;
}
_storeCoordinator = psc;
*/
}
return _storeCoordinator;
}
#pragma mark - iCloud Related Methods -
// Subscribe to NSPersistentStoreDidImportUbiquitousContentChangesNotification
- (void)persistentStoreDidImportUbiquitousContentChanges:(NSNotification*)note
{
NSLog(@"%s", __PRETTY_FUNCTION__);
NSLog(@"%@", note.userInfo.description);
NSManagedObjectContext *moc = self.mainContext;
[moc performBlock:^{
[moc mergeChangesFromContextDidSaveNotification:note];
DLog(@"NSPersistentStoreDidImportUbiquitousContentChangesNotification executed");
/*
// you may want to post a notification here so that which ever part of your app
// needs to can react appropriately to what was merged.
// An exmaple of how to iterate over what was merged follows, although I wouldn't
// recommend doing it here. Better handle it in a delegate or use notifications.
// Note that the notification contains NSManagedObjectIDs
// and not NSManagedObjects.
NSDictionary *changes = note.userInfo;
NSMutableSet *allChanges = [NSMutableSet new];
[allChanges unionSet:changes[NSInsertedObjectsKey]];
[allChanges unionSet:changes[NSUpdatedObjectsKey]];
[allChanges unionSet:changes[NSDeletedObjectsKey]];
for (NSManagedObjectID *objID in allChanges) {
// do whatever you need to with the NSManagedObjectID
// you can retrieve the object from with [moc objectWithID:objID]
}
*/
}];
}
// Subscribe to NSPersistentStoreCoordinatorStoresWillChangeNotification
// most likely to be called if the user enables / disables iCloud
// (either globally, or just for your app) or if the user changes
// iCloud accounts.
- (void)storesWillChange:(NSNotification *)note {
NSManagedObjectContext *moc = self.mainContext;
[moc performBlockAndWait:^{
NSError *error = nil;
if ([moc hasChanges]) {
[moc save:&error];
}
[moc reset];
}];
// now reset your UI to be prepared for a totally different
// set of data (eg, popToRootViewControllerAnimated:)
// but don't load any new data yet.
[[NSNotificationCenter defaultCenter] postNotificationName:@"notifCoreDataStoreWillChange" object:nil];
DLog(@"storeWillChange notification fire");
}
// Subscribe to NSPersistentStoreCoordinatorStoresDidChangeNotification
- (void)storesDidChange:(NSNotification *)note
{
// here is when you can refresh your UI and
// load new data from the new store
[[NSNotificationCenter defaultCenter] postNotificationName:@"notifCoreDataStoreDidChange" object:nil];
DLog(@"storeDidChange notification fire");
}
#pragma mark - Entity Fetching Methods -
-(NSArray *)fetchEntityOfType:(NSString *)entityType UsingPredicated:(NSPredicate *)predicate sortBy:(NSString *)sortKey ascendingOrder:(BOOL)ascendingOrder
{
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entityType inManagedObjectContext:[[MLSAlbumsDataModel sharedModel] mainContext]];
NSSortDescriptor *sortDescriptor = nil;
if(sortKey)
{
sortDescriptor = [[NSSortDescriptor alloc] initWithKey:sortKey ascending:ascendingOrder];
}
else
{
sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"updatedAt" ascending:ascendingOrder];
}
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = entityDescription;
if(predicate)
{
request.predicate = predicate;
}
request.sortDescriptors = @[sortDescriptor];
NSError *error = nil;
NSArray *results = [[[MLSAlbumsDataModel sharedModel] mainContext] executeFetchRequest:request error:&error];
if(results == nil)
{
DLog(@"Error getting entity of type '%@' using predicate '%@', sortKey '%@' ascendingOrder %d", entityType, predicate, sortKey, ascendingOrder);
}
return results;
}
I tried to run the app on the iPad Simulator (I believe it is the iOS 8 simulator) and on iPad device running iOS 7.x
I created an album with a user entered name on the simulator, but I am not seeing the iPad device showing the newly created album. I also tried reversing the roles, iPad device create, iOS simulator no results either.
I do see my log messages:
storeDidChange notification fire
SQLITE STORE PATH: /Users/xxxxxxx/Library/Developer/CoreSimulator/Devices/3DC17576-92E9-4EAF-B77A-41340AE28F92/data/Containers/Data/Application/E51085CE-3772-4DF1-A503-1C243497091A/Documents/Albums.sqlite
If I minimise the app in the simulator and open it again (without pressing the Stop button in Xcode), I see these message:
-[PFUbiquitySwitchboardEntryMetadata setUseLocalStorage:](808): CoreData: Ubiquity: nobody~sim301AE3E8-16B2-5A08-917D-7B55D1879BE4:iCloudStore
Using local storage: 1
I read that "Using local storage: 0" is what it should ideally be? and that 1 means local device data store rather than iCloud data store.
When I create an album, save it, stop the simulator, then start the app again, my albums disappears, but immediately after I create a new album, all the previous album reappear magically again. It's a bit odd. If I don't use iCloud and revert my code to previous setup, I can create and see my album fine, regardless of whether I minimise my app or not, or restart app, but then I don't have iCloud sync which I need.
Have I made any mistakes anywhere?
Sorry for the long post but has anyone got iCloud working for iOS 8 and Xcode 6 ?
I could really use some help.
1) Does iOS 8 require the use of this container identifier ? (which Xcode 6 generated for me):
com.apple.developer.icloud-container-identifiers
That's not what the iOS 7 one looks like right? iOS 7 one is more like:
com.apple.developer.ubiquity-container-identifiers
2) Do I need an iCloud Drive account before it works?
Super confused @_@
OK...then....lol. I think I solved it.
New discovery. After skimming through this page:
http://www.tuaw.com/2014/09/17/psa-do-not-upgrade-to-icloud-drive-during-ios-8-installation/
It says:
iCloud Drive is Apple's new and improved iCloud syncing and file storage feature that allows you to share documents between your iOS 8 devices and your Mac running OS X 10 Yosemite.
So, I decided to bite the bullet and upgrade my iCloud account to iCloud drive (free to upgrade).
After upgrading to iCloud drive, and re-ran my app with a few Xcode 6 changes, it's working now.
Some Important Things to note:
For the above reason, I changed to using a Ubiquity container with this pattern:
iCloud.$(CFBundleIdentifier)
So something like:
iCloud.com.xxxxxxxx.iCloudCoreDataDemo
Where "xxxxxxxx" is my company name identifier.
I made the above iCloud container by logging into my iOS Developer Center, perhaps you could just press the "+" sign inside Xcode 6 and enter one there, Xcode should automagically setup everything for you.
One block of code I used to test to see if it's working is this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.persistentStack = [[PersistentStack alloc] initWithStoreURL:self.storeURL modelURL:self.modelURL];
self.managedObjectContext = self.persistentStack.managedObjectContext;
NSURL *containerURL = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:@"iCloud.com.xxxxxxxxxx.iCloudCoreDataDemo"];
if(containerURL == nil)
{
NSLog(@"containerURL == nil");
}
else
{
NSLog(@"hurray?");
}
return YES;
}
If you see "hurray?" then it's fine, you should also see this pattern of text in your Xcode console output:
2014-10-07 17:37:23.196 iCloudCoreDataDemo[8104:130250] documentsDirectory = file:///Users/xxxxxxxx/Library/Developer/CoreSimulator/Devices/9FAFE881-13CA-4608-8BE6-728C793FAFFB/data/Containers/Data/Application/BC6CA07D-605A-4927-94AF-E9E21E204D2B/Documents/
2014-10-07 17:37:23.386 iCloudCoreDataDemo[8104:130250] storeDidChange
2014-10-07 17:37:23.390 iCloudCoreDataDemo[8104:130250] -[PFUbiquitySwitchboardEntryMetadata setUseLocalStorage:](808): CoreData: Ubiquity: nobody~sim301AE3E8-16B2-5A08-917D-7B55D1879BE4:iCloudStore
Using local storage: 1
2014-10-07 17:37:23.402 iCloudCoreDataDemo[8104:130250] hurray?
2014-10-07 17:37:33.909 iCloudCoreDataDemo[8104:130250] storeWillChange
2014-10-07 17:37:33.933 iCloudCoreDataDemo[8104:130250] storeDidChange
2014-10-07 17:37:33.933 iCloudCoreDataDemo[8104:130330] -[PFUbiquitySwitchboardEntryMetadata setUseLocalStorage:](808): CoreData: Ubiquity: nobody~sim301AE3E8-16B2-5A08-917D-7B55D1879BE4:iCloudStore
Using local storage: 0
Notice the two important lines:
Using local storage: 1
later becomes:
Using local storage: 0
Local storage 1 means it's currently using local storage, while local storage 0 means it has moved the data to iCloud storage.
I hope this benefits everyone else.
OK, so I've just discovered something and managed to get it working for iOS 7 only. I still haven't figured out how to do it in iOS 8 but I have noticed something important.
On my iPhone 5 running iOS 8.0.2, I don't have the "Document & Data" option inside the iCloud settings menu anymore.
However, on my iPad running iOS 7, I DO see the "Document & Data" options.
Perhaps this is the reason why it doesn't work on iOS 8, we no longer have Document & Data storage ?
Anyhow, here's what I discovered for iOS 7 only solution.
I found this page here
and one of the line says:
Sure enough, I went into my Xcode 6 project file and ticked the "iCloud Documents" option. This un-greyed the radio buttons, but I still left it at "Use default Containers".
One thing I learned is that I need to init my PersistentStack in the appDelegate. Previously, I tried to init the persistent stack inside the +(id)sharedInstance method but it caused the iCloud to only sync the first time, so after initial load and sync, adding new record doesn't get synced afterwards.
I rewrote a basic app and modified the persistent stack slightly:
#import <UIKit/UIKit.h>
#import "PersistentStack.h"
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (nonatomic, strong) NSManagedObjectContext* managedObjectContext;
@property (nonatomic, strong) PersistentStack* persistentStack;
@end
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.persistentStack = [[PersistentStack alloc] initWithStoreURL:self.storeURL modelURL:self.modelURL];
self.managedObjectContext = self.persistentStack.managedObjectContext;
return YES;
}
...
- (NSURL*)storeURL
{
NSURL* documentsDirectory = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:YES error:NULL];
return [documentsDirectory URLByAppendingPathComponent:@"MyApp.sqlite"];
}
- (NSURL*)modelURL
{
return [[NSBundle mainBundle] URLForResource:@"MyApp" withExtension:@"momd"];
}
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#import "Book.h"
#import <UIKit/UIKit.h>
@interface PersistentStack : NSObject
+(id)sharedInstance;
- (id)initWithStoreURL:(NSURL *)storeURL modelURL:(NSURL *)modelURL;
@property (nonatomic,strong,readonly) NSManagedObjectContext *managedObjectContext;
#pragma mark - Regular Methods -
-(Book *)insertNewBookWithDate:(NSDate *)newDate;
-(void)deleteBook:(Book *)book;
-(NSArray *)fetchEntityOfType:(NSString *)entityType withPredicate:(NSPredicate *)predicate andSortKey:(NSString *)sortKey;
@end
#import "PersistentStack.h"
#import "AppDelegate.h"
@interface PersistentStack ()
@property (nonatomic,strong,readwrite) NSManagedObjectContext* managedObjectContext;
@property (nonatomic,strong) NSURL* modelURL;
@property (nonatomic,strong) NSURL* storeURL;
@end
@implementation PersistentStack
+(id)sharedInstance
{
static PersistentStack *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
sharedInstance = appDelegate.persistentStack;
});
return sharedInstance;
}
- (id)initWithStoreURL:(NSURL*)storeURL modelURL:(NSURL*)modelURL
{
self = [super init];
if (self) {
self.storeURL = storeURL;
self.modelURL = modelURL;
[self setupManagedObjectContext];
}
return self;
}
- (void)setupManagedObjectContext
{
self.managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
self.managedObjectContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy;
self.managedObjectContext.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
//__weak NSPersistentStoreCoordinator *psc = self.managedObjectContext.persistentStoreCoordinator;
// iCloud notification subscriptions
NSNotificationCenter *dc = [NSNotificationCenter defaultCenter];
[dc addObserver:self
selector:@selector(storesWillChange:)
name:NSPersistentStoreCoordinatorStoresWillChangeNotification
object:self.managedObjectContext.persistentStoreCoordinator];
[dc addObserver:self
selector:@selector(storesDidChange:)
name:NSPersistentStoreCoordinatorStoresDidChangeNotification
object:self.managedObjectContext.persistentStoreCoordinator];
[dc addObserver:self
selector:@selector(persistentStoreDidImportUbiquitousContentChanges:)
name:NSPersistentStoreDidImportUbiquitousContentChangesNotification
object:self.managedObjectContext.persistentStoreCoordinator];
NSError* error;
// the only difference in this call that makes the store an iCloud enabled store
// is the NSPersistentStoreUbiquitousContentNameKey in options. I use "iCloudStore"
// but you can use what you like. For a non-iCloud enabled store, I pass "nil" for options.
// Note that the store URL is the same regardless of whether you're using iCloud or not.
// If you create a non-iCloud enabled store, it will be created in the App's Documents directory.
// An iCloud enabled store will be created below a directory called CoreDataUbiquitySupport
// in your App's Documents directory
[self.managedObjectContext.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:self.storeURL
options:@{ NSPersistentStoreUbiquitousContentNameKey : @"iCloudStore" }
error:&error];
if (error) {
NSLog(@"error: %@", error);
}
}
- (NSManagedObjectModel*)managedObjectModel
{
return [[NSManagedObjectModel alloc] initWithContentsOfURL:self.modelURL];
}
// Subscribe to NSPersistentStoreDidImportUbiquitousContentChangesNotification
- (void)persistentStoreDidImportUbiquitousContentChanges:(NSNotification*)note
{
NSLog(@"%s", __PRETTY_FUNCTION__);
NSLog(@"%@", note.userInfo.description);
NSManagedObjectContext *moc = self.managedObjectContext;
[moc performBlock:^{
[moc mergeChangesFromContextDidSaveNotification:note];
[[NSNotificationCenter defaultCenter] postNotificationName:@"notifiCloudStoreDidChange" object:nil];
/*
// you may want to post a notification here so that which ever part of your app
// needs to can react appropriately to what was merged.
// An exmaple of how to iterate over what was merged follows, although I wouldn't
// recommend doing it here. Better handle it in a delegate or use notifications.
// Note that the notification contains NSManagedObjectIDs
// and not NSManagedObjects.
NSDictionary *changes = note.userInfo;
NSMutableSet *allChanges = [NSMutableSet new];
[allChanges unionSet:changes[NSInsertedObjectsKey]];
[allChanges unionSet:changes[NSUpdatedObjectsKey]];
[allChanges unionSet:changes[NSDeletedObjectsKey]];
for (NSManagedObjectID *objID in allChanges) {
// do whatever you need to with the NSManagedObjectID
// you can retrieve the object from with [moc objectWithID:objID]
}
*/
}];
}
// Subscribe to NSPersistentStoreCoordinatorStoresWillChangeNotification
// most likely to be called if the user enables / disables iCloud
// (either globally, or just for your app) or if the user changes
// iCloud accounts.
- (void)storesWillChange:(NSNotification *)note {
NSLog(@"storeWillChange");
NSManagedObjectContext *moc = self.managedObjectContext;
//[moc performBlockAndWait:^{
[moc performBlock:^{
NSError *error = nil;
if ([moc hasChanges]) {
[moc save:&error];
}
[moc reset];
}];
// now reset your UI to be prepared for a totally different
// set of data (eg, popToRootViewControllerAnimated:)
// but don't load any new data yet.
}
// Subscribe to NSPersistentStoreCoordinatorStoresDidChangeNotification
- (void)storesDidChange:(NSNotification *)note {
// here is when you can refresh your UI and
// load new data from the new store
NSLog(@"storeDidChange");
[[NSNotificationCenter defaultCenter] postNotificationName:@"notifiCloudStoreDidChange" object:nil];
}
#pragma mark - Regular Methods -
-(Book *)insertNewBookWithDate:(NSDate *)newDate
{
Book *newBook = [NSEntityDescription insertNewObjectForEntityForName:@"Book" inManagedObjectContext:self.managedObjectContext];
newBook.bookName = @"Book";
newBook.publishDate = newDate;
[self.managedObjectContext save:nil];
return newBook;
}
-(void)deleteBook:(Book *)book
{
[self.managedObjectContext deleteObject:book];
[self.managedObjectContext save:nil];
}
-(NSArray *)fetchEntityOfType:(NSString *)entityType withPredicate:(NSPredicate *)predicate andSortKey:(NSString *)sortKey
{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:entityType inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Specify criteria for filtering which objects to fetch
[fetchRequest setPredicate:predicate];
// Specify how the fetched objects should be sorted
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:sortKey
ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObjects:sortDescriptor, nil]];
NSError *error = nil;
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil)
{
NSLog(@"couldn't fetch entity of type '%@', error: %@", entityType, error.localizedDescription);
}
return fetchedObjects;
}
@end