iOS sqlite storing null value without calling setValue - ios

Question

I am trying to store product in sqlite. When i setValue for database entity then i store correct value.
But problem is that i make a check if product is already in database then it should not add same product again. But next time it store NULL value in database.
Although i am not calling [addToFav setValue:#"My Value"];
Simply its check in for loop. When my loop runs it won't go in first condition where i make counter if(count == 0)
I don't know where from its storing NULL value. While i am not calling it any where else. So how its storing NULL value in database ?
- (IBAction)buttonAddToFavourite:(id)sender {
int count = 0;
NSManagedObjectContext *context = [self managedObjectContext];
NSError *error=nil;
NSManagedObject *addToFav = [NSEntityDescription insertNewObjectForEntityForName:#"Favourite" inManagedObjectContext:context];
NSString *dish = [results objectForKey:#"id"];
fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Favourite" inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *info in fetchedObjects) {
NSString *id1 = [info valueForKey:#"dishid"];
if ([id1 isEqualToString:dish]) {
count = count +1;
}
}
if (count == 0) {
[addToFav setValue:[results objectForKey:#"id"] forKey:#"dishid"];
[CSNotificationView showInViewController:self
tintColor:[UIColor greenColor]
image:[UIImage imageNamed:#"sucess"]
message:#"Saved As Favourite."
duration:2.0f];
[self.permanentNotification setShowingActivity:YES];
}
else if (count > 0){
[CSNotificationView showInViewController:self
tintColor:[UIColor redColor]
image:[UIImage imageNamed:#"warning"]
message:#"Dish Already Added."
duration:2.0f];
[self.permanentNotification setShowingActivity:YES];
}
if (![context save:&error]) {
NSLog(#"Can't Save! %# %#", error, [error localizedDescription]);
}
}

Answer 1

- (IBAction)buttonAddToFavourite:(id)sender {
NSError *error = nil;
NSString *dishId = results[#"id"];
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:#"Favourite"];
[fetchRequest setPredicate:[NSPredicate predicateWithFormat:#"dishid == %#", dishId]];
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects.count) {
[CSNotificationView showInViewController:self
tintColor:[UIColor redColor]
image:[UIImage imageNamed:#"warning"]
message:#"Dish Already Added."
duration:2.0f];
[self.permanentNotification setShowingActivity:YES];
}
else {
Favourite *obj = [NSEntityDescription insertNewObjectForEntityForName:#"Favourite" inManagedObjectContext:self.managedObjectContext];
obj.dishid = dishId;
[CSNotificationView showInViewController:self
tintColor:[UIColor greenColor]
image:[UIImage imageNamed:#"sucess"]
message:#"Saved As Favourite."
duration:2.0f];
[self.permanentNotification setShowingActivity:YES];
if (![context save:&error]) {
NSLog(#"Can't Save! %# %#", error, [error localizedDescription]);
}
}
}