Array Not Deleting Duplicates - ios

Question

I am trying to make it to where an array loads items into a table view from core data. Some of the values are duplicates though. So, within the array that I am using to fetch the data, I am trying to tell the array to remove any duplicates and then display it in the table view. But for some reason it is not removing the duplicates. Here is the code:
UPDATED
- (void)viewDidLoad
{
fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *weightEntity = [NSEntityDescription entityForName:#"Tracking" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:weightEntity];
result = [self.managedObjectContext executeFetchRequest:fetchRequest error:nil];
NSMutableArray *cleaningArray= [NSMutableArray new];
NSSet *duplicatesRemover = [NSSet setWithArray:result];
[duplicatesRemover enumerateObjectsUsingBlock: ^(id obj, BOOL* stop)
{
if(![cleaningArray containsObject: obj])
{
[cleaningArray addObject: obj];
}
}];
cleanArray = [cleaningArray copy];
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
mainCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (mainCell == nil) {
mainCell = [[dictionaryTableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
Entity *person = [cleanArray objectAtIndex:indexPath.row];
mainCell.nameLabel.text = person.date;
return mainCell;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"%#", [cleanArray objectAtIndex:0]);
return cleanArray.count;
}
Thanks!

Answer 1

-containsObject compares strings (as in [string1 isEqual:string2]) so you could do this
NSArray* result = #[#"test",#"string",#"test",#"line"];
NSMutableArray* cleanArray = [[NSMutableArray alloc] init];
for (id object in result) {
if (![cleanArray containsObject:object])
[cleanArray addObject:object];
}
NSLog (#"cleanArray %#",cleanArray);
log:
cleanArray (
test,
string,
line
)
update
#dreamlax and I been chatting with #Zack. It seems the NSSet / isEqual issue was a red herring. The "result" array does not contain NSStrings, it contains fetch requests for Core Data, each of which are of course unique, even if the data returned isn't. This array is tightly coupled with the table view, which executes those fetch requests ... on request.
So what Zack needed to do was to decouple Core Data from his Table View, pre-fetch the strings he wants to compare for uniqueness, and feed that uniqued array to the Table View. NSSet works fine for obtaining a unique set of results.
fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *weightEntity =
[NSEntityDescription entityForName:#"Entity"
inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:weightEntity];
result = [self.managedObjectContext executeFetchRequest:fetchRequest
error:nil];
NSMutableSet *dateSet = [NSMutableSet alloc] init];
for (id object in result) {
Entity *person = object;
NSString* dateString = person.date;
[dateSet addObject:dateString];
}
self.dateArray = [dateSet allObjects];
Then in his tableView:
mainCell.nameLabel.text = [cleanArray objectAtIndex:indexPath.row];

Answer 2

With credits to dreamlax, It's a matter of overriding the isEqual: method, that's why NSSet doesn't remove your duplicate objects.
In your entity, override the isEqual method and return true if all the fields are equal, for example:
- (BOOL)isEqual:(id)anObject
{
return self.attribute_1 == anObject,attribute_1 && ... && self.attribute_N== anObject.attribute_N; // Primitive types comparison in this example
}