CoreData objects not saved between screens - ios

Question

I have a screen that holds a UITableView, in this screen I have an array of NSManagedObjects. It's working just fine, but as I try move to another screen (click on a specific cell, and push a new screen), then return to the same UITableView screen, all the objects got lost.
What does it means? I try to print the array of the NSManagedObjects and it's fine, all the objects there, but as I print the description of each object, I get nil from all the object attributes.
Someone knows whats the cause of it? I don't know why but it worked just fine 12 hours ago, but now it's all messed up and I don't have a clue what have I done.
Thanks in advance!
Save method:
- (void)saveContext {
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = 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();
}
else {
NSLog(#"Context saved!");
}
}
}
This is how I save the objects:
NSDictionary *response = responseObject;
if ([[response valueForKey:#"status"] rangeOfString:#"ok"].location != NSNotFound)
{
NSArray *data = [response objectForKey:#"data"];
if (data.count != 0)
{
if (page.integerValue == 0) {
[[DownloadData sharedData] deleteAllObjectsFromEntityName:#"DbHomeCuisine"];
[[DownloadData sharedData] deleteAllObjectsFromEntityName:#"DbHomeCategory"];
[[DownloadData sharedData] deleteAllObjectsFromEntityName:#"DbHomeDish"];
}
NSMutableArray *homePageObjects = [[NSMutableArray alloc] initWithCapacity:data.count];
for (NSDictionary *object in data)
{
NSNumber *type = [object objectForKey:#"type"];
switch (type.integerValue) {
case 1:
{
NSDictionary *content = [object objectForKey:#"content"];
NSManagedObjectContext *context = [[MainDb sharedDb] managedObjectContext];
DbHomeCuisine *homeCuisine = [NSEntityDescription insertNewObjectForEntityForName:#"DbHomeCuisine" inManagedObjectContext:context];
NSInteger cuisineId = [[content valueForKey:#"cuisine_id"] integerValue];
homeCuisine.cuisine = [self gCuisineWithCuisineId:[NSNumber numberWithInteger:cuisineId]];
NSInteger count = [[content valueForKey:#"count"] integerValue];
homeCuisine.count = [NSNumber numberWithInteger:count];
homeCuisine.type = type;
[homePageObjects addObject:homeCuisine];
}
break;
case 2:
{
NSDictionary *content = [object objectForKey:#"content"];
NSManagedObjectContext *context = [[MainDb sharedDb] managedObjectContext];
DbHomeCategory *homeCategory = [NSEntityDescription insertNewObjectForEntityForName:#"DbHomeCategory" inManagedObjectContext:context];
NSInteger categoryId = [[content valueForKey:#"category_id"] integerValue];
homeCategory.category = [self gCategoryWithCategoryId:[NSNumber numberWithInteger:categoryId]];
NSInteger count = [[content valueForKey:#"count"] integerValue];
homeCategory.count = [NSNumber numberWithInteger:count];
homeCategory.type = type;
[homePageObjects addObject:homeCategory];
}
break;
case 3:
{
NSDictionary *content = [object objectForKey:#"content"];
NSManagedObjectContext *context = [[MainDb sharedDb] managedObjectContext];
DbHomeDish *homeDish = [NSEntityDescription insertNewObjectForEntityForName:#"DbHomeDish" inManagedObjectContext:context];
homeDish.dishId = [self gInt:content forKey:#"dish_id"];
homeDish.headline = [AppUtils checkForEmptyValue:[content valueForKey:#"title"]];
homeDish.text = [AppUtils checkForEmptyValue:[content valueForKey:#"description"]];
homeDish.cuisineId = [self gInt:content forKey:#"cuisine_id"];
homeDish.cuisine = [self gCuisineWithCuisineId:homeDish.cuisineId];
homeDish.creationDate = [AppUtils checkForEmptyValue:[content valueForKey:#"creation_time"]];
homeDish.userId = [self gInt:content forKey:#"user_id"];
homeDish.longitude = [self gDouble:content forKey:#"lng"];
homeDish.latitude = [self gDouble:content forKey:#"lat"];
homeDish.lastPromoteDate = [AppUtils checkForEmptyValue:[content valueForKey:#"last_promote_time"]];
homeDish.price = [self gInt:content forKey:#"price"];
homeDish.currency = [AppUtils checkForEmptyValue:[content valueForKey:#"currency"]];
homeDish.countryName = [AppUtils checkForEmptyValue:[content valueForKey:#"country_name"]];
homeDish.baseCurrency = [self gFloat:content forKey:#"base_currency"];
homeDish.exchangeRate = [self gFloat:content forKey:#"exchange_rate"];
homeDish.countryIsoCode = [AppUtils checkForEmptyValue:[content valueForKey:#"country_iso_code"]];
homeDish.mainPhoto = [AppUtils checkForEmptyValue:[content valueForKey:#"main_photo"]];
homeDish.like = [self gLikeWithDishId:homeDish.dishId];
homeDish.profileImageURL = [AppUtils checkForEmptyValue:[content valueForKey:#"profile_img_url"]];
homeDish.likeCount = [self gInt:content forKey:#"likes"];
homeDish.type = type;
[homePageObjects addObject:homeDish];
}
break;
default:
break;
}
}
// ##log -- Save data to core data and device
//
//
[[MainDb sharedDb] saveContext];
if (success) {
success(operation, homePageObjects);
}
}
}

Answer 1

Seriously, you should consider refactoring using a NSFetchedResultsController. Start from the template provided in Xcode (New Project -> Master/Detail -> check Core Data, the code is in MasterViewController.m).
I strongly discourage loading Core Data objects into an array to be displayed in a table view. Your problem is typical for such a setup, and you will run into memory and performance issues eventually as well.