Core Data Backgrounding

coredata.m

#import "HiveDeviceCoreDataManager.h"

static HiveDeviceCoreDataManager* globalManager = nil;

NSString *const HiveDeviceCoreDataRefetchAllDatabaseData = @"DeviceRefetchAllDatabaseData";

@implementation HiveDeviceCoreDataManager

@synthesize mainContext = _mainContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
@synthesize initialized = _isInitialized;

///////////////////////////////////////////////////////////////////////////////////////////////////
+ (HiveDeviceCoreDataManager*)globalManager {
    return globalManager;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
+ (void)setGlobalManager:(HiveDeviceCoreDataManager*)manager {
    if (globalManager!=manager) {
        globalManager = manager;
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)saveDataInBackgroundWithContext:(void(^)(NSManagedObjectContext *context))saveBlock completion:(void(^)(void))completion
{
    if(!self.initialized){
        return;
    }
    
    NSManagedObjectContext *childContext = [[NSManagedObjectContext alloc]initWithConcurrencyType:NSPrivateQueueConcurrencyType];
    [childContext setParentContext:self.mainContext];
    [childContext performBlock:^{
        saveBlock(childContext);
        if ([childContext hasChanges])
        {
            NSError* error = nil;
            if ([childContext hasChanges] && ![childContext save:&error])
            {
                HIVETRACKERRORFORMAT(error,@"HiveCoreDataManager Error Saving Child Context %@, %@", error, [error userInfo]);
            }
        }
        dispatch_sync(dispatch_get_main_queue(), ^(void) {
            completion();
        });
    }];
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSManagedObjectModel *)managedObjectModel
{
    if (!_managedObjectModel)
    {
        NSURL *modelURL = [[NSBundle mainBundle] URLForResource:SETTINGS(dataModelFileName) withExtension:@"momd"];
        _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    }
    return _managedObjectModel;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (!_persistentStoreCoordinator)
    {
        _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
        [self loadPersistantStore];
    }
    return _persistentStoreCoordinator;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSManagedObjectContext *)mainContext
{
    if (!_mainContext)
    {
        if (self.persistentStoreCoordinator)
        {
            _mainContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
            [_mainContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
            [_mainContext setMergePolicy:NSMergeByPropertyStoreTrumpMergePolicy];
        }
    }
    return _mainContext;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
-(BOOL) saveContext{
    return [self saveContext:self.mainContext];
}

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

#pragma mark -
#pragma mark Public Methods

///////////////////////////////////////////////////////////////////////////////////////////////////
-(void)initialize {
    
    //default implementation does nothing.
    //To be overridden
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)didInitialize {
    
    //default implementation does nothing
    //To be overridden
}


///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)registerForNotifications {
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationWillTerminate:)
                                                 name:UIApplicationWillTerminateNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationWillResignActive:)
                                                 name:UIApplicationWillResignActiveNotification object:nil];
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)deleteAllObjectsWithEntityDescription:(NSEntityDescription*)entity inContext:(NSManagedObjectContext*)context{
    
    if(!self.initialized||!context){
        return;
    }
    
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
        [request setEntity:entity];
        
    NSError *error = nil;
    NSArray *objectsToDelete = [context executeFetchRequest:request error:&error];
    
    if(objectsToDelete){
        for(id objectToDelete in objectsToDelete){
            [context deleteObject:objectToDelete];
        }
        [self saveContext:context];
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)deleteAllObjectsWithEntityDescription:(NSEntityDescription*)entity{
    [self deleteAllObjectsWithEntityDescription:entity inContext:self.mainContext];
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (BOOL)saveContext:(NSManagedObjectContext*)context
{
    if(!self.initialized||!context){
        return NO;
    }
    
    @try {
        NSError *error = nil;
        if ([context hasChanges])
        {
            BOOL saved = [context save:&error];
            
            if(error||!saved){
                HIVETRACKERRORFORMAT(error,@"HiveDeviceCoreDataManager Error Saving Context %@ - %@,%@",context, error, [error userInfo]);
                return NO;
            }
            
            if([context parentContext]){
                [[context parentContext] save:&error];
                if(error||!saved){
                    HIVETRACKERRORFORMAT(error,@"HiveDeviceCoreDataManager Error Saving Parent Context %@ - %@,%@",context, error, [error userInfo]);
                    return NO;
                }
            }
        }
    }
    @catch (NSException *exception) {
        HIVETRACKEXCEPTIONDESC(exception, @"Exception saving context");
        return NO;
    }
    return YES;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSArray*)executeFetchRequest:(NSFetchRequest*)request inContext:(NSManagedObjectContext*)context{
    
    if(!context){
        return nil;
    }
    
    @try {
        
        NSError* error = nil;
        NSArray *results = [context executeFetchRequest:request error:&error];
        
        if (!error&&TTIsArrayWithItems(results)){
            return results;
        } else {
            if(error){
                HIVETRACKERRORDESC(error,@"Error executing fetch request");
            }
            return nil;
        }
    }
    @catch (NSException *exception) {
        HIVETRACKEXCEPTIONDESC(exception, @"Exception executing fetch request");
        return nil;
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSInteger)findCountForFetchRequest:(NSFetchRequest*)request inContext:(NSManagedObjectContext*)context{
    
    if(!context){
        return 0;
    }
    
    @try {
        
        NSError* error = nil;
        NSInteger count = [context countForFetchRequest:request error:&error];

        if (!error){
            return count;
        } else {
            HIVETRACKERRORDESC(error,@"Error finding count for fetch request");
            return 0;
        }
    }
    @catch (NSException *exception) {
        HIVETRACKEXCEPTIONDESC(exception, @"Exception finding count for fetch request");
        return 0;
    }
}


#pragma mark -
#pragma mark Private

///////////////////////////////////////////////////////////////////////////////////////////////////
-(void) loadPersistantStore{
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        
        NSURL *storeURL = [[self applicationDocumentsDirectory]
                           URLByAppendingPathComponent:[NSString stringWithFormat:@"%@_Device.sqlite",SETTINGS(appName)]];
        NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                                 [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                                 [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
                                 nil];
        NSError *error = nil;
        if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error])
        {
            HIVETRACKERRORDESC(error,@"HNCoreDataManager Error Loading PersistantStore");
        } else {
            
            [self initialize];
            dispatch_sync(dispatch_get_main_queue(), ^{
                _isInitialized = YES;
                [self didInitialize];
                [self registerForNotifications];
                [[NSNotificationCenter defaultCenter] postNotificationName:HiveDeviceCoreDataRefetchAllDatabaseData object:self userInfo:nil];
            });
        }
    });
}

#pragma mark -
#pragma mark Notifications

///////////////////////////////////////////////////////////////////////////////////////////////////
-(void)applicationWillTerminate:(NSNotification*)notification{
    TTDINFO(@"Saving Context because application will terminate");
    [self saveContext];
}

///////////////////////////////////////////////////////////////////////////////////////////////////
-(void)applicationWillResignActive:(NSNotification*)notification{
    TTDINFO(@"Saving Context because application will resign active");
    [self saveContext];
}

@end