iOS : Core Data - Get Unique Attributes from Core Data

GetUniqueCoreDataElements.m

NSManagedObjectContext *context = <#Get the context#>;
 
NSEntityDescription *entity = [NSEntityDescription  entityForName:@"<#Entity name#>" inManagedObjectContext:context];
 
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entity];
[request setResultType:NSDictionaryResultType];
[request setReturnsDistinctResults:YES];
[request setPropertiesToFetch:@[@"<#Attribute name#>"]];
 
// Execute the fetch.
NSError *error;
id requestedValue = nil;
NSArray *objects = [context executeFetchRequest:request error:&error];
if (objects == nil) {
    // Handle the error.
}