Core Data - Fetch doesn't deliver the same result - ios

Question

So I'm adding a ListItem into ListName(There is a one to many relationship setted up) in a Class A
ListItem *newItem = [NSEntityDescription insertNewObjectForEntityForName:#"ListItem"
inManagedObjectContext:self.context];
//setting some attributes...
[listName addListItemsObject:newItem];
[self.context save:&error];
After that Class B is via a delegate methode called
There I want to get the data out of Core Data, BUT...If I'm fetching all ListName, the ListItems are not up to date(for example only 5 items instead of 6). If I fetch all ListItems then there are all there(6 out of 6).
What is wrong with my code...I need to get all ListNames though
NSError *error;
NSFetchRequest *req = [[NSFetchRequest alloc] init];
if(context == nil)
NSLog(#"context is nil");
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListName" inManagedObjectContext:self.context];
[req setEntity:descr];
NSSortDescriptor *sort = [[NSSortDescriptor alloc]initWithKey:#"lastModified" ascending:NO];
[req setSortDescriptors:[NSArray arrayWithObject:sort]];
NSArray * results = [self.context executeFetchRequest:req error:&error];
self.listNames = [results mutableCopy];
if ([results count] > 0) {
ListName *test = [results objectAtIndex:0];
[test.listItems count];
NSLog(#"item count on list %i", [test.listItems count]);
//wrong result
NSFetchRequest *newReq = [[NSFetchRequest alloc] init];
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListItem" inManagedObjectContext:self.context];
[newReq setEntity:descr];
NSArray * results2 = [self.context executeFetchRequest:newReq error:&error];
NSLog(#"item count on items %i", [results2 count]);
//right result
}

Answer 1

Given your data model and code, there is no reason that the count of ListItems in both places as to be the same because the counts are of two different sets of objects that do not necessarily overlap.
The first count is given by this code:
ListName *test = [results objectAtIndex:0];
[test.listItems count];
… which returns the count of ListItems objects in the relationship of a single, particular and unique ListName object. You may have one ListName object or you might have hundreds each of which could have an arbitrary number of related ListItems objects. This code will only count those related to he first ListName object returned.
The second count is given by:
NSFetchRequest *newReq = [[NSFetchRequest alloc] init];
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListItem" inManagedObjectContext:self.context];
[newReq setEntity:descr];
NSArray * results2 = [self.context executeFetchRequest:newReq error:&error];
NSLog(#"item count on items %i", [results2 count]);
… which returns an unfiltered array containing every instance of ListItems in the persistent store regardless of what relationships they have.
There is no particular reason to expect the first count to ever agree with the second because it will only do so when (1) you have a single ListNames object in the store and (2) every existing ListItems object is in that ListNames.listNames relationship.
Make sure not confuse entities and managed objects.
BTW, you should almost always use reciprocal relationships e.g. if you have ListNames.listItems you should have a reciprocal ListItems.listName.

Answer 2

A simple reset has helped