How to save data loaded from core data in array?

Question

I use below code in my code for fetching data from CoreData:

id appdelegate = [UIApplication sharedApplication].delegate;
NSManagedObjectContext *managedObjectContext = [appdelegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"TelePayment" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"index" ascending:YES];
[fetchRequest setSortDescriptors:@[sort]];
NSError *error = nil;
 Items = [managedObjectContext executeFetchRequest:fetchRequest error:&error];

It seems that when I change my CoreData entity (deleting items) the Items array also changes? Is it correct?

If yes, how can I avoid this?

Answer 1

You need to create a wrapper class that would be instantiated using core data entity and work with objects of that class in your code.

For example, if you have such entity

@interface Item: NSManagedObject
  NSInteger id;
  NSString *name;
@end

You should create a class

@interface ItemObject: NSObject
  NSInteger itemId;
  NSString *itemName;
@end

@implementation ItemObject

  - (void)initWithEntity:(NSManagedObject*)entity {
    self = [super init];
    if (self) {
      _itemId = entity.id;
      _itemName = entity.name;
    }
    return self;
  }
@end

UPDATE: (duplicate comment here for better readability)

...
Items = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
NSMutableArray *newArray = [NSMutableArray new];
for (NSManagedObject *object in items) {
  ItemObject *newItem = [[ItemObject alloc] initWithEntity:object];
  [newArray addObject:newItem];
}

Than you work with newArray.