How to persist an MSMutableArray in Core Data? - ios

Question

I use Core Data and fetch objects into a NSMutableArray:
NSError *error;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Item" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
self.items = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy];
I then use this mutable array to display objects in a table view. Moreover the data in that array gets changed overtime. I would like to persist that whole array in Core Data.
My initial idea was to remove all items from Core Data and by itterating over all objects in the mutable array persist them one at a time:
- (void)persistAllItemsInCoreData{
[self clearAllItemsFromCoreData];
NSManagedObjectContext *context = [self managedObjectContext];
for(int i = 0 ; i < [items count] ; i++){
Item *item = [NSEntityDescription
insertNewObjectForEntityForName:#"Item"
inManagedObjectContext:context];
item = [items objectAtIndex:i];
}
NSError *error;
if (![context save:&error]) {
NSLog(#"Could not save data: %#", [error localizedDescription]);
}
}
Howover, that doesn't work. Is there a more elegant way to persist an NSMutableArray using Core Data?

Answer 1

The items in the array are already in Core Data. If you change them you just need to save them. If you add an item to that array then you need to create a new NSManagedObject instance and put it into the array.
Your code implies that you do not understand the fundamentals of Core Data. I would highly recommend reviewing the documentation on this framework to get a better understanding of it.